[PATCH 0/2] Add support for DS90UB954-Q1

[PATCH 0/2] Add support for DS90UB954-Q1

[Yemike Abhilash Chandra]

DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
compatible with DS90UB960-Q1. The main difference is that it supports
half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
port. Therefore, add support for DS90UB954 within the existing DS90UB960
bindings and the driver.

Test logs: https://gist.github.com/Yemike-Abhilash-Chandra/e7af7b4f5a4e6304dd572e3a691e8b98

Note: Few differences between the DS90UB960 and DS90UB954 leveraged in this series
were originally explored in an earlier submission [1], which was not merged due to
the contributor being under the Russian ban list. We acknowledge the efforts made
in that submission [1].

[1]: https://lore.kernel.org/all/20241015080737.16272-2-eagle.alexander923@gmail.com/

Yemike Abhilash Chandra (2):
  media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1
  media: i2c: ds90ub960: Add support for DS90UB954-Q1

 .../bindings/media/i2c/ti,ds90ub960.yaml      |  1 +
 drivers/media/i2c/Kconfig                     |  2 +-
 drivers/media/i2c/ds90ub960.c                 | 46 +++++++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

-- 
2.34.1

[PATCH 1/2] media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1

[Yemike Abhilash Chandra]

DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
compatible with DS90UB960-Q1. The main difference is that it supports
half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
port. Therefore, add support for DS90UB954 within the existing bindings.

Link: https://www.ti.com/lit/gpn/ds90ub954-q1
Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
---
 Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
index 4dcbd2b039a5..b2d4300d7846 100644
--- a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
+++ b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
@@ -19,6 +19,7 @@ allOf:
 properties:
   compatible:
     enum:
+      - ti,ds90ub954-q1
       - ti,ds90ub960-q1
       - ti,ds90ub9702-q1
 
-- 
2.34.1

Re: [PATCH 1/2] media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1

[Conor Dooley]

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Acked-by: Conor Dooley <conor.dooley@microchip.com>

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Re: [PATCH 1/2] media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1

[Tomi Valkeinen]

Hi,

On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
> compatible with DS90UB960-Q1. The main difference is that it supports
> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
> port. Therefore, add support for DS90UB954 within the existing bindings.
> 
> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
> ---
>  Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
> index 4dcbd2b039a5..b2d4300d7846 100644
> --- a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
> +++ b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
> @@ -19,6 +19,7 @@ allOf:
>  properties:
>    compatible:
>      enum:
> +      - ti,ds90ub954-q1
>        - ti,ds90ub960-q1
>        - ti,ds90ub9702-q1
>  

Does this pass the dt checks? The binding lists ports 0-5 as required.

 Tomi

Re: [PATCH 1/2] media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1

[Yemike Abhilash Chandra]

Hi Tomi,

Thanks for the review.

On 27/05/25 10:30, Tomi Valkeinen wrote:
> Hi,
> 
> On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>> compatible with DS90UB960-Q1. The main difference is that it supports
>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>> port. Therefore, add support for DS90UB954 within the existing bindings.
>>
>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> ---
>>   Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>> index 4dcbd2b039a5..b2d4300d7846 100644
>> --- a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>> +++ b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>> @@ -19,6 +19,7 @@ allOf:
>>   properties:
>>     compatible:
>>       enum:
>> +      - ti,ds90ub954-q1
>>         - ti,ds90ub960-q1
>>         - ti,ds90ub9702-q1
>>   
> 
> Does this pass the dt checks? The binding lists ports 0-5 as required.

Thanks for pointing this out. It is passing DT checks since we have marked
port 4 and port 5 as disabled in DT, but I now understand that approach is
not acceptable.

Ports 0–3 are documented as FPD-Link inputs, but on UB954, only ports 0 
and 1 are inputs,
while port 2 is CSI TX. Should I conditionally modify required ports for 
UB954(0-2) and
UB960/UB9702 (0-5), even though port 2's description would mismatch?
(In bindings it would be described as FPD-Link input but it will be 
modeled as CSI TX in DT).

Alternatively, we can describe the ports block separately for each 
compatible to
ensure correctness. Please let me know which approach you prefer.

Thanks and Regards,
Abhilash Chandra


> 
>   Tomi
> 

Re: [PATCH 1/2] media: dt-bindings: ti,ds90ub960: Add bindings for DS90UB954-Q1

[Tomi Valkeinen]

Hi,

On 28/05/2025 08:35, Yemike Abhilash Chandra wrote:
> Hi Tomi,
> 
> Thanks for the review.
> 
> On 27/05/25 10:30, Tomi Valkeinen wrote:
>> Hi,
>>
>> On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
>>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>>> compatible with DS90UB960-Q1. The main difference is that it supports
>>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>>> port. Therefore, add support for DS90UB954 within the existing bindings.
>>>
>>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>>> ---
>>>   Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/media/i2c/
>>> ti,ds90ub960.yaml b/Documentation/devicetree/bindings/media/i2c/
>>> ti,ds90ub960.yaml
>>> index 4dcbd2b039a5..b2d4300d7846 100644
>>> --- a/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>>> +++ b/Documentation/devicetree/bindings/media/i2c/ti,ds90ub960.yaml
>>> @@ -19,6 +19,7 @@ allOf:
>>>   properties:
>>>     compatible:
>>>       enum:
>>> +      - ti,ds90ub954-q1
>>>         - ti,ds90ub960-q1
>>>         - ti,ds90ub9702-q1
>>>   
>>
>> Does this pass the dt checks? The binding lists ports 0-5 as required.
> 
> Thanks for pointing this out. It is passing DT checks since we have marked
> port 4 and port 5 as disabled in DT, but I now understand that approach is
> not acceptable.
> 
> Ports 0–3 are documented as FPD-Link inputs, but on UB954, only ports 0
> and 1 are inputs,
> while port 2 is CSI TX. Should I conditionally modify required ports for
> UB954(0-2) and
> UB960/UB9702 (0-5), even though port 2's description would mismatch?
> (In bindings it would be described as FPD-Link input but it will be
> modeled as CSI TX in DT).
> 
> Alternatively, we can describe the ports block separately for each
> compatible to
> ensure correctness. Please let me know which approach you prefer.

I think you have two options here: either use ports 0, 1, 2 for UB954,
or use ports 0, 1, 4 for UB954. I think the first option makes more sense.

The bindings have to be correct, you can't do "even though port 2's
description would mismatch". Probably the clearest way is just to have a
conditional and define all the ports separately for ub954 and for the rest.

You can check e.g. renesas,du.yaml, which does rather complex conditionals.

I do wonder, though, if the port definitions could be more brief by
somehow defining the RX and TX port details only once, instead of
replicating the same for every port.

Note that the bindings also allow link0-3, which for UB954 should be
link0-1.

 Tomi

[PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Yemike Abhilash Chandra]

DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
compatible with DS90UB960-Q1. The main difference is that it supports
half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
port.

Some other registers are marked as reserved in the datasheet as well,
notably around CSI-TX frame and line-count monitoring and some other
status registers. The datasheet also does not mention anything about
setting strobe position, and fails to lock the RX ports if we forcefully
set it, so disable it through the hw_data.

Link: https://www.ti.com/lit/gpn/ds90ub954-q1
Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
---
 drivers/media/i2c/Kconfig     |  2 +-
 drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index e68202954a8f..6e265e1cec20 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
 	select V4L2_FWNODE
 	select VIDEO_V4L2_SUBDEV_API
 	help
-	  Device driver for the Texas Instruments DS90UB960
+	  Device driver for the Texas Instruments DS90UB954/DS90UB960
 	  FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.
 
 config VIDEO_MAX96714
diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
index ed2cf9d247d1..38e4f006d098 100644
--- a/drivers/media/i2c/ds90ub960.c
+++ b/drivers/media/i2c/ds90ub960.c
@@ -460,6 +460,7 @@ struct ub960_hw_data {
 	u8 num_txports;
 	bool is_ub9702;
 	bool is_fpdlink4;
+	bool is_ub954;
 };
 
 enum ub960_rxport_mode {
@@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data *priv, u8 nport)
 
 	lockdep_assert_held(&priv->reg_lock);
 
+	/* TX port registers are shared for UB954*/
+	if (priv->hw_data->is_ub954)
+		return 0;
+
 	if (priv->reg_current.txport == nport)
 		return 0;
 
@@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct ub960_data *priv,
 		goto err_free_vep;
 	}
 
+	/* UB954 does not support 1.2 Gbps */
+	if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
+		dev_err(dev, "tx%u: invalid 'link-frequencies' value\n", nport);
+		ret = -EINVAL;
+		goto err_free_vep;
+	}
+
 	v4l2_fwnode_endpoint_free(&vep);
 
 	priv->txports[nport] = txport;
@@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct ub960_data *priv,
 	u8 clk_delay, data_delay;
 	int ret = 0;
 
+	/* FIXME: After writing to this area the UB954 chip no longer responds */
+	if (priv->hw_data->is_ub954)
+		return 0;
+
 	clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
 	data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
 
@@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct ub960_data *priv)
 	if (priv->hw_data->is_ub9702)
 		ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
 				 NULL);
+	else if (priv->hw_data->is_ub954) {
+		/* From DS90UB954-Q1 datasheet:
+		 * "REFCLK_FREQ measurement is not synchronized. Value in this
+		 * register should read twice and only considered valid if
+		 * REFCLK_FREQ is unchanged between reads."
+		 */
+		unsigned long timeout = jiffies + msecs_to_jiffies(100);
+
+		do {
+			u8 refclk_new;
+
+			ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
+					 NULL);
+			if (ret)
+				goto err_pd_gpio;
+
+			if (refclk_new == refclk_freq)
+				break;
+			refclk_freq = refclk_new;
+		} while (time_before(jiffies, timeout));
+	}
 	else
 		ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
 				 NULL);
@@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client *client)
 	mutex_destroy(&priv->reg_lock);
 }
 
+static const struct ub960_hw_data ds90ub954_hw = {
+	.model = "ub954",
+	.num_rxports = 2,
+	.num_txports = 1,
+	.is_ub954 = true,
+};
+
 static const struct ub960_hw_data ds90ub960_hw = {
 	.model = "ub960",
 	.num_rxports = 4,
@@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw = {
 };
 
 static const struct i2c_device_id ub960_id[] = {
+	{ "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
 	{ "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
 	{ "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
 	{}
@@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
 MODULE_DEVICE_TABLE(i2c, ub960_id);
 
 static const struct of_device_id ub960_dt_ids[] = {
+	{ .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
 	{ .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
 	{ .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
 	{}
-- 
2.34.1

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Jai Luthra]

Hi Abhilash,

Thanks for the patch.

Quoting Yemike Abhilash Chandra (2025-05-23 14:06:55)
> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
> compatible with DS90UB960-Q1. The main difference is that it supports
> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
> port.
> 
> Some other registers are marked as reserved in the datasheet as well,
> notably around CSI-TX frame and line-count monitoring and some other
> status registers. The datasheet also does not mention anything about

So what happens when userspace calls LOG_STATUS and the driver tries to
read these monitoring registers? Are these populated in the device but just
marked as reserved in the datasheet?

Whatever is the case, please make sure the driver doesn't crash, and update
the commit message with the reality if the datasheet is wrong.

> setting strobe position, and fails to lock the RX ports if we forcefully
> set it, so disable it through the hw_data.
> 
> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
> ---
>  drivers/media/i2c/Kconfig     |  2 +-
>  drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index e68202954a8f..6e265e1cec20 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>         select V4L2_FWNODE
>         select VIDEO_V4L2_SUBDEV_API
>         help
> -         Device driver for the Texas Instruments DS90UB960
> +         Device driver for the Texas Instruments DS90UB954/DS90UB960
>           FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.

nit:
           Device driver for the Texas Instruments DS90UB954, DS90UB960
           FPD-Link III Deserializers and DS90UB9702 FPD-Link IV Deserializer.

>  
>  config VIDEO_MAX96714
> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
> index ed2cf9d247d1..38e4f006d098 100644
> --- a/drivers/media/i2c/ds90ub960.c
> +++ b/drivers/media/i2c/ds90ub960.c
> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>         u8 num_txports;
>         bool is_ub9702;
>         bool is_fpdlink4;
> +       bool is_ub954;
>  };
>  
>  enum ub960_rxport_mode {
> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data *priv, u8 nport)
>  
>         lockdep_assert_held(&priv->reg_lock);
>  
> +       /* TX port registers are shared for UB954*/
> +       if (priv->hw_data->is_ub954)
> +               return 0;
> +

nit: This could be moved above the assertion

>         if (priv->reg_current.txport == nport)
>                 return 0;
>  
> @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct ub960_data *priv,
>                 goto err_free_vep;
>         }
>  
> +       /* UB954 does not support 1.2 Gbps */
> +       if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
> +               dev_err(dev, "tx%u: invalid 'link-frequencies' value\n", nport);
> +               ret = -EINVAL;
> +               goto err_free_vep;
> +       }
> +

The error handling is exactly the same as the previous if {} block that
checks the allowed data rates for UB960. IMO cleaner to move this condition
in that block.

Maybe even a separate table for allowed data-rates for each chip, but that
is probably overkill.

>         v4l2_fwnode_endpoint_free(&vep);
>  
>         priv->txports[nport] = txport;
> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct ub960_data *priv,
>         u8 clk_delay, data_delay;
>         int ret = 0;
>  
> +       /* FIXME: After writing to this area the UB954 chip no longer responds */
> +       if (priv->hw_data->is_ub954)
> +               return 0;
> +

It would be good to understand if this is a hardware limitation or not.
Tomi, do you have any idea?

>         clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>         data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>  
> @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct ub960_data *priv)
>         if (priv->hw_data->is_ub9702)
>                 ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>                                  NULL);
> +       else if (priv->hw_data->is_ub954) {
> +               /* From DS90UB954-Q1 datasheet:
> +                * "REFCLK_FREQ measurement is not synchronized. Value in this
> +                * register should read twice and only considered valid if

                   * register should be read twice and only considered valid if

> +                * REFCLK_FREQ is unchanged between reads."
> +                */
> +               unsigned long timeout = jiffies + msecs_to_jiffies(100);
> +
> +               do {
> +                       u8 refclk_new;
> +
> +                       ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
> +                                        NULL);
> +                       if (ret)
> +                               goto err_pd_gpio;
> +
> +                       if (refclk_new == refclk_freq)
> +                               break;
> +                       refclk_freq = refclk_new;
> +               } while (time_before(jiffies, timeout));
> +       }

Hmm.. in your testing did you find this actually requiring more than one
read?

I'm surprised because this is missing from UB960 which is an older device.

>         else
>                 ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>                                  NULL);
> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client *client)
>         mutex_destroy(&priv->reg_lock);
>  }
>  
> +static const struct ub960_hw_data ds90ub954_hw = {
> +       .model = "ub954",
> +       .num_rxports = 2,
> +       .num_txports = 1,
> +       .is_ub954 = true,
> +};
> +
>  static const struct ub960_hw_data ds90ub960_hw = {
>         .model = "ub960",
>         .num_rxports = 4,
> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw = {
>  };
>  
>  static const struct i2c_device_id ub960_id[] = {
> +       { "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>         { "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>         { "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>         {}
> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>  MODULE_DEVICE_TABLE(i2c, ub960_id);
>  
>  static const struct of_device_id ub960_dt_ids[] = {
> +       { .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>         { .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>         { .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>         {}
> -- 
> 2.34.1
> 
>

Thanks,
Jai

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Yemike Abhilash Chandra]

Hi Jai,

Thanks for the review.

On 23/05/25 22:23, Jai Luthra wrote:
> Hi Abhilash,
> 
> Thanks for the patch.
> 
> Quoting Yemike Abhilash Chandra (2025-05-23 14:06:55)
>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>> compatible with DS90UB960-Q1. The main difference is that it supports
>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>> port.
>>
>> Some other registers are marked as reserved in the datasheet as well,
>> notably around CSI-TX frame and line-count monitoring and some other
>> status registers. The datasheet also does not mention anything about
> 
> So what happens when userspace calls LOG_STATUS and the driver tries to
> read these monitoring registers? Are these populated in the device but just
> marked as reserved in the datasheet?
> 
> Whatever is the case, please make sure the driver doesn't crash, and update
> the commit message with the reality if the datasheet is wrong.
> 

I don't see a crash while doing a log-status [1]. In the driver, we 
check what
TX and RX ports are active from the HW data and the do a register read
accordingly. That should be fine I believe.

>> setting strobe position, and fails to lock the RX ports if we forcefully
>> set it, so disable it through the hw_data.
>>
>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> ---
>>   drivers/media/i2c/Kconfig     |  2 +-
>>   drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>>   2 files changed, 47 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index e68202954a8f..6e265e1cec20 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>>          select V4L2_FWNODE
>>          select VIDEO_V4L2_SUBDEV_API
>>          help
>> -         Device driver for the Texas Instruments DS90UB960
>> +         Device driver for the Texas Instruments DS90UB954/DS90UB960
>>            FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.
> 
> nit:
>             Device driver for the Texas Instruments DS90UB954, DS90UB960
>             FPD-Link III Deserializers and DS90UB9702 FPD-Link IV Deserializer.
> 
>>   
>>   config VIDEO_MAX96714
>> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
>> index ed2cf9d247d1..38e4f006d098 100644
>> --- a/drivers/media/i2c/ds90ub960.c
>> +++ b/drivers/media/i2c/ds90ub960.c
>> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>>          u8 num_txports;
>>          bool is_ub9702;
>>          bool is_fpdlink4;
>> +       bool is_ub954;
>>   };
>>   
>>   enum ub960_rxport_mode {
>> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data *priv, u8 nport)
>>   
>>          lockdep_assert_held(&priv->reg_lock);
>>   
>> +       /* TX port registers are shared for UB954*/
>> +       if (priv->hw_data->is_ub954)
>> +               return 0;
>> +
> 
> nit: This could be moved above the assertion

Will do that in next revision.

> 
>>          if (priv->reg_current.txport == nport)
>>                  return 0;
>>   
>> @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct ub960_data *priv,
>>                  goto err_free_vep;
>>          }
>>   
>> +       /* UB954 does not support 1.2 Gbps */
>> +       if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
>> +               dev_err(dev, "tx%u: invalid 'link-frequencies' value\n", nport);
>> +               ret = -EINVAL;
>> +               goto err_free_vep;
>> +       }
>> +
> 
> The error handling is exactly the same as the previous if {} block that
> checks the allowed data rates for UB960. IMO cleaner to move this condition
> in that block.
> 

Noted, will try to do that in a cleaner way in next revision.

> Maybe even a separate table for allowed data-rates for each chip, but that
> is probably overkill.
> 
>>          v4l2_fwnode_endpoint_free(&vep);
>>   
>>          priv->txports[nport] = txport;
>> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct ub960_data *priv,
>>          u8 clk_delay, data_delay;
>>          int ret = 0;
>>   
>> +       /* FIXME: After writing to this area the UB954 chip no longer responds */
>> +       if (priv->hw_data->is_ub954)
>> +               return 0;
>> +
> 
> It would be good to understand if this is a hardware limitation or not.
> Tomi, do you have any idea?
> 
>>          clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>>          data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>>   
>> @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct ub960_data *priv)
>>          if (priv->hw_data->is_ub9702)
>>                  ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>>                                   NULL);
>> +       else if (priv->hw_data->is_ub954) {
>> +               /* From DS90UB954-Q1 datasheet:
>> +                * "REFCLK_FREQ measurement is not synchronized. Value in this
>> +                * register should read twice and only considered valid if
> 
>                     * register should be read twice and only considered valid if
> 
>> +                * REFCLK_FREQ is unchanged between reads."
>> +                */
>> +               unsigned long timeout = jiffies + msecs_to_jiffies(100);
>> +
>> +               do {
>> +                       u8 refclk_new;
>> +
>> +                       ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
>> +                                        NULL);
>> +                       if (ret)
>> +                               goto err_pd_gpio;
>> +
>> +                       if (refclk_new == refclk_freq)
>> +                               break;
>> +                       refclk_freq = refclk_new;
>> +               } while (time_before(jiffies, timeout));
>> +       }
> 
> Hmm.. in your testing did you find this actually requiring more than one
> read?
> 
> I'm surprised because this is missing from UB960 which is an older device.
> 

In my testing (around 20 reboots) , I had to do only 1 check i.e just 2
iterations. I am not sure on how to proceed but the data sheet at7.6.121 
REFCLK_FREQ Register clearly specifies the below.

"REFCLK_FREQ measurement is not synchronized. Value in this
register should read twice and only considered valid if
REFCLK_FREQ is unchanged between reads."


Thanks and Regards,
Abhilash Chandra

[1]: 
https://gist.github.com/Yemike-Abhilash-Chandra/dc07a6389d06648d9e80de23d8cae954

>>          else
>>                  ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>>                                   NULL);
>> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client *client)
>>          mutex_destroy(&priv->reg_lock);
>>   }
>>   
>> +static const struct ub960_hw_data ds90ub954_hw = {
>> +       .model = "ub954",
>> +       .num_rxports = 2,
>> +       .num_txports = 1,
>> +       .is_ub954 = true,
>> +};
>> +
>>   static const struct ub960_hw_data ds90ub960_hw = {
>>          .model = "ub960",
>>          .num_rxports = 4,
>> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw = {
>>   };
>>   
>>   static const struct i2c_device_id ub960_id[] = {
>> +       { "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>>          { "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>>          { "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>>          {}
>> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>>   MODULE_DEVICE_TABLE(i2c, ub960_id);
>>   
>>   static const struct of_device_id ub960_dt_ids[] = {
>> +       { .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>>          { .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>>          { .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>>          {}
>> -- 
>> 2.34.1
>>
>>
> 
> Thanks,
> Jai

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Tomi Valkeinen]

Hi,

On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
> compatible with DS90UB960-Q1. The main difference is that it supports
> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
> port.
> 
> Some other registers are marked as reserved in the datasheet as well,
> notably around CSI-TX frame and line-count monitoring and some other

Hmm what does that mean? That in log_status we show random data (or
maybe always 0) for these?

> status registers. The datasheet also does not mention anything about
> setting strobe position, and fails to lock the RX ports if we forcefully
> set it, so disable it through the hw_data.

This app-note has some details:

https://www.ti.com/lit/an/snla301/snla301.pdf

> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
> ---
>  drivers/media/i2c/Kconfig     |  2 +-
>  drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index e68202954a8f..6e265e1cec20 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>  	select V4L2_FWNODE
>  	select VIDEO_V4L2_SUBDEV_API
>  	help
> -	  Device driver for the Texas Instruments DS90UB960
> +	  Device driver for the Texas Instruments DS90UB954/DS90UB960
>  	  FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.
>  
>  config VIDEO_MAX96714
> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
> index ed2cf9d247d1..38e4f006d098 100644
> --- a/drivers/media/i2c/ds90ub960.c
> +++ b/drivers/media/i2c/ds90ub960.c
> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>  	u8 num_txports;
>  	bool is_ub9702;
>  	bool is_fpdlink4;
> +	bool is_ub954;

No, let's not add any more of these. We should have enums for the device
model and the "family" (ub954/ub960 are clearly of the same family,
whereas ub9702 is of a newer one).

>  };
>  
>  enum ub960_rxport_mode {
> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data *priv, u8 nport)
>  
>  	lockdep_assert_held(&priv->reg_lock);
>  
> +	/* TX port registers are shared for UB954*/

Space missing at the end. What does the comment mean? "registers are
shared"?

I think it's good to have this after the lockdep assert. The lock rules
are in place, even if on ub954 we don't do anything here.

> +	if (priv->hw_data->is_ub954)
> +		return 0;
> +
>  	if (priv->reg_current.txport == nport)
>  		return 0;
>  
> @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct ub960_data *priv,
>  		goto err_free_vep;
>  	}
>  
> +	/* UB954 does not support 1.2 Gbps */
> +	if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {

Test for ub954 first, 1200 MHz second. It's more logical for the reader
that way.

> +		dev_err(dev, "tx%u: invalid 'link-frequencies' value\n", nport);
> +		ret = -EINVAL;
> +		goto err_free_vep;
> +	}
> +
>  	v4l2_fwnode_endpoint_free(&vep);
>  
>  	priv->txports[nport] = txport;
> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct ub960_data *priv,
>  	u8 clk_delay, data_delay;
>  	int ret = 0;
>  
> +	/* FIXME: After writing to this area the UB954 chip no longer responds */
> +	if (priv->hw_data->is_ub954)
> +		return 0;
> +

Check the app note. It would be nice to have this working, as, afaik,
the HW functionality should be the same on ub954 and ub960.

>  	clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>  	data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>  
> @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct ub960_data *priv)
>  	if (priv->hw_data->is_ub9702)
>  		ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>  				 NULL);
> +	else if (priv->hw_data->is_ub954) {
> +		/* From DS90UB954-Q1 datasheet:
> +		 * "REFCLK_FREQ measurement is not synchronized. Value in this
> +		 * register should read twice and only considered valid if
> +		 * REFCLK_FREQ is unchanged between reads."
> +		 */
> +		unsigned long timeout = jiffies + msecs_to_jiffies(100);
> +
> +		do {
> +			u8 refclk_new;
> +
> +			ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
> +					 NULL);
> +			if (ret)
> +				goto err_pd_gpio;
> +
> +			if (refclk_new == refclk_freq)
> +				break;
> +			refclk_freq = refclk_new;
> +		} while (time_before(jiffies, timeout));
> +	}

This feels a bit too much for a not-that-important debug print... As the
tests show that a single read is (practically always?) enough, I think
we can just use the same code as for ub960. Maybe add a comment about
it, though.

 Tomi

>  	else
>  		ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>  				 NULL);
> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client *client)
>  	mutex_destroy(&priv->reg_lock);
>  }
>  
> +static const struct ub960_hw_data ds90ub954_hw = {
> +	.model = "ub954",
> +	.num_rxports = 2,
> +	.num_txports = 1,
> +	.is_ub954 = true,
> +};
> +
>  static const struct ub960_hw_data ds90ub960_hw = {
>  	.model = "ub960",
>  	.num_rxports = 4,
> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw = {
>  };
>  
>  static const struct i2c_device_id ub960_id[] = {
> +	{ "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>  	{ "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>  	{ "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>  	{}
> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>  MODULE_DEVICE_TABLE(i2c, ub960_id);
>  
>  static const struct of_device_id ub960_dt_ids[] = {
> +	{ .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>  	{ .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>  	{ .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>  	{}

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Yemike Abhilash Chandra]

Hi Tomi,

Thanks for the review.

On 27/05/25 11:10, Tomi Valkeinen wrote:
> Hi,
> 
> On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>> compatible with DS90UB960-Q1. The main difference is that it supports
>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>> port.
>>
>> Some other registers are marked as reserved in the datasheet as well,
>> notably around CSI-TX frame and line-count monitoring and some other
> 
> Hmm what does that mean? That in log_status we show random data (or
> maybe always 0) for these?
> 

It seems like it is showing 0's for these. I streamed around 100 frames.
But the frame counter and line counter returned is 0. Please find the
logs at [1].

>> status registers. The datasheet also does not mention anything about
>> setting strobe position, and fails to lock the RX ports if we forcefully
>> set it, so disable it through the hw_data.
> 
> This app-note has some details:
> 
> https://www.ti.com/lit/an/snla301/snla301.pdf
> 
>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> ---
>>   drivers/media/i2c/Kconfig     |  2 +-
>>   drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>>   2 files changed, 47 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index e68202954a8f..6e265e1cec20 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>>   	select V4L2_FWNODE
>>   	select VIDEO_V4L2_SUBDEV_API
>>   	help
>> -	  Device driver for the Texas Instruments DS90UB960
>> +	  Device driver for the Texas Instruments DS90UB954/DS90UB960
>>   	  FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.
>>   
>>   config VIDEO_MAX96714
>> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
>> index ed2cf9d247d1..38e4f006d098 100644
>> --- a/drivers/media/i2c/ds90ub960.c
>> +++ b/drivers/media/i2c/ds90ub960.c
>> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>>   	u8 num_txports;
>>   	bool is_ub9702;
>>   	bool is_fpdlink4;
>> +	bool is_ub954;
> 
> No, let's not add any more of these. We should have enums for the device
> model and the "family" (ub954/ub960 are clearly of the same family,
> whereas ub9702 is of a newer one).
> 

Got it. I will add enums in the next revision.

>>   };
>>   
>>   enum ub960_rxport_mode {
>> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data *priv, u8 nport)
>>   
>>   	lockdep_assert_held(&priv->reg_lock);
>>   
>> +	/* TX port registers are shared for UB954*/
> 
> Space missing at the end. What does the comment mean? "registers are
> shared"?
> 

Apologies for the inaccurate comment description, My intention to
comment that the tx_port_select function does not make sense for
UB954, since we have only 1 CSI TX. May be I can have something
like below.

/** UB954 has only 1 CSI TX. Hence, no need to select **/

> I think it's good to have this after the lockdep assert. The lock rules
> are in place, even if on ub954 we don't do anything here.
> 
>> +	if (priv->hw_data->is_ub954)
>> +		return 0;
>> +
>>   	if (priv->reg_current.txport == nport)
>>   		return 0;
>>   
>> @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct ub960_data *priv,
>>   		goto err_free_vep;
>>   	}
>>   
>> +	/* UB954 does not support 1.2 Gbps */
>> +	if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
> 
> Test for ub954 first, 1200 MHz second. It's more logical for the reader
> that way.
> 

Noted, will do that in the next revision.

>> +		dev_err(dev, "tx%u: invalid 'link-frequencies' value\n", nport);
>> +		ret = -EINVAL;
>> +		goto err_free_vep;
>> +	}
>> +
>>   	v4l2_fwnode_endpoint_free(&vep);
>>   
>>   	priv->txports[nport] = txport;
>> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct ub960_data *priv,
>>   	u8 clk_delay, data_delay;
>>   	int ret = 0;
>>   
>> +	/* FIXME: After writing to this area the UB954 chip no longer responds */
>> +	if (priv->hw_data->is_ub954)
>> +		return 0;
>> +
> 
> Check the app note. It would be nice to have this working, as, afaik,
> the HW functionality should be the same on ub954 and ub960.
> 

I tried referring the app note and changed the strobe position values
accordingly, but it did not help.

Since the app note also specifies the below at Table 2 Strobe Adaption Modes

"
AEQ Adaption Mode--> Strobe position is selected as part of AEQ. This is 
the default mode.

Manual Adaption Mode --> The strobe position is selected manually and 
will remain at
the specified position until a new one is chosen. This mode is 
recommended as an
evaluation and debugging mode "

Since, under the default settings, the strobe position is selected as 
part of the AEQ process.
Can we limit the ub960_rxport_set_strobe_pos function to only UB960 and 
UB9702.

>>   	clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>>   	data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>>   
>> @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct ub960_data *priv)
>>   	if (priv->hw_data->is_ub9702)
>>   		ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>>   				 NULL);
>> +	else if (priv->hw_data->is_ub954) {
>> +		/* From DS90UB954-Q1 datasheet:
>> +		 * "REFCLK_FREQ measurement is not synchronized. Value in this
>> +		 * register should read twice and only considered valid if
>> +		 * REFCLK_FREQ is unchanged between reads."
>> +		 */
>> +		unsigned long timeout = jiffies + msecs_to_jiffies(100);
>> +
>> +		do {
>> +			u8 refclk_new;
>> +
>> +			ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
>> +					 NULL);
>> +			if (ret)
>> +				goto err_pd_gpio;
>> +
>> +			if (refclk_new == refclk_freq)
>> +				break;
>> +			refclk_freq = refclk_new;
>> +		} while (time_before(jiffies, timeout));
>> +	}
> 
> This feels a bit too much for a not-that-important debug print... As the
> tests show that a single read is (practically always?) enough, I think
> we can just use the same code as for ub960. Maybe add a comment about
> it, though.
> 

okay, I will use the same code that is being used for UB960 and will add 
a comment
about that.

Thanks and Regards,
Abhilash Chandra

[1]: 
https://gist.github.com/Yemike-Abhilash-Chandra/c6b3da2a10586567a3a4179a2b20d21b

>   Tomi
> 
>>   	else
>>   		ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>>   				 NULL);
>> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client *client)
>>   	mutex_destroy(&priv->reg_lock);
>>   }
>>   
>> +static const struct ub960_hw_data ds90ub954_hw = {
>> +	.model = "ub954",
>> +	.num_rxports = 2,
>> +	.num_txports = 1,
>> +	.is_ub954 = true,
>> +};
>> +
>>   static const struct ub960_hw_data ds90ub960_hw = {
>>   	.model = "ub960",
>>   	.num_rxports = 4,
>> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw = {
>>   };
>>   
>>   static const struct i2c_device_id ub960_id[] = {
>> +	{ "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>>   	{ "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>>   	{ "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>>   	{}
>> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>>   MODULE_DEVICE_TABLE(i2c, ub960_id);
>>   
>>   static const struct of_device_id ub960_dt_ids[] = {
>> +	{ .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>>   	{ .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>>   	{ .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>>   	{}
> 

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Tomi Valkeinen]

Hi,

On 28/05/2025 09:25, Yemike Abhilash Chandra wrote:
> Hi Tomi,
> 
> Thanks for the review.
> 
> On 27/05/25 11:10, Tomi Valkeinen wrote:
>> Hi,
>>
>> On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
>>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>>> compatible with DS90UB960-Q1. The main difference is that it supports
>>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>>> port.
>>>
>>> Some other registers are marked as reserved in the datasheet as well,
>>> notably around CSI-TX frame and line-count monitoring and some other
>>
>> Hmm what does that mean? That in log_status we show random data (or
>> maybe always 0) for these?
>>
> 
> It seems like it is showing 0's for these. I streamed around 100 frames.
> But the frame counter and line counter returned is 0. Please find the
> logs at [1].

If the registers are marked as reserved and don't function, we should
not use them. Here it doesn't do any harm when running the code, but it
does decrease the usefulness of log_status if the user is shown data
that is wrong (and the user most likely doesn't know it's wrong).

>>> status registers. The datasheet also does not mention anything about
>>> setting strobe position, and fails to lock the RX ports if we forcefully
>>> set it, so disable it through the hw_data.
>>
>> This app-note has some details:
>>
>> https://www.ti.com/lit/an/snla301/snla301.pdf
>>
>>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>>> ---
>>>   drivers/media/i2c/Kconfig     |  2 +-
>>>   drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>>>   2 files changed, 47 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>>> index e68202954a8f..6e265e1cec20 100644
>>> --- a/drivers/media/i2c/Kconfig
>>> +++ b/drivers/media/i2c/Kconfig
>>> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>>>       select V4L2_FWNODE
>>>       select VIDEO_V4L2_SUBDEV_API
>>>       help
>>> -      Device driver for the Texas Instruments DS90UB960
>>> +      Device driver for the Texas Instruments DS90UB954/DS90UB960
>>>         FPD-Link III Deserializer and DS90UB9702 FPD-Link IV
>>> Deserializer.
>>>     config VIDEO_MAX96714
>>> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/
>>> ds90ub960.c
>>> index ed2cf9d247d1..38e4f006d098 100644
>>> --- a/drivers/media/i2c/ds90ub960.c
>>> +++ b/drivers/media/i2c/ds90ub960.c
>>> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>>>       u8 num_txports;
>>>       bool is_ub9702;
>>>       bool is_fpdlink4;
>>> +    bool is_ub954;
>>
>> No, let's not add any more of these. We should have enums for the device
>> model and the "family" (ub954/ub960 are clearly of the same family,
>> whereas ub9702 is of a newer one).
>>
> 
> Got it. I will add enums in the next revision.
> 
>>>   };
>>>     enum ub960_rxport_mode {
>>> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data
>>> *priv, u8 nport)
>>>         lockdep_assert_held(&priv->reg_lock);
>>>   +    /* TX port registers are shared for UB954*/
>>
>> Space missing at the end. What does the comment mean? "registers are
>> shared"?
>>
> 
> Apologies for the inaccurate comment description, My intention to
> comment that the tx_port_select function does not make sense for
> UB954, since we have only 1 CSI TX. May be I can have something
> like below.
> 
> /** UB954 has only 1 CSI TX. Hence, no need to select **/
> 
>> I think it's good to have this after the lockdep assert. The lock rules
>> are in place, even if on ub954 we don't do anything here.
>>
>>> +    if (priv->hw_data->is_ub954)
>>> +        return 0;
>>> +
>>>       if (priv->reg_current.txport == nport)
>>>           return 0;
>>>   @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct
>>> ub960_data *priv,
>>>           goto err_free_vep;
>>>       }
>>>   +    /* UB954 does not support 1.2 Gbps */
>>> +    if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
>>
>> Test for ub954 first, 1200 MHz second. It's more logical for the reader
>> that way.
>>
> 
> Noted, will do that in the next revision.
> 
>>> +        dev_err(dev, "tx%u: invalid 'link-frequencies' value\n",
>>> nport);
>>> +        ret = -EINVAL;
>>> +        goto err_free_vep;
>>> +    }
>>> +
>>>       v4l2_fwnode_endpoint_free(&vep);
>>>         priv->txports[nport] = txport;
>>> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct
>>> ub960_data *priv,
>>>       u8 clk_delay, data_delay;
>>>       int ret = 0;
>>>   +    /* FIXME: After writing to this area the UB954 chip no longer
>>> responds */
>>> +    if (priv->hw_data->is_ub954)
>>> +        return 0;
>>> +
>>
>> Check the app note. It would be nice to have this working, as, afaik,
>> the HW functionality should be the same on ub954 and ub960.
>>
> 
> I tried referring the app note and changed the strobe position values
> accordingly, but it did not help.
> 
> Since the app note also specifies the below at Table 2 Strobe Adaption
> Modes
> 
> "
> AEQ Adaption Mode--> Strobe position is selected as part of AEQ. This is
> the default mode.
> 
> Manual Adaption Mode --> The strobe position is selected manually and
> will remain at
> the specified position until a new one is chosen. This mode is
> recommended as an
> evaluation and debugging mode "
> 
> Since, under the default settings, the strobe position is selected as
> part of the AEQ process.
> Can we limit the ub960_rxport_set_strobe_pos function to only UB960 and
> UB9702.

Ok. But it doesn't sound good if we just skip the
ub960_rxport_set_strobe_pos(), but keep all the other EQ related writes.
I.e. we do the EQ config partially, and leave out parts that, for
unknown reasons, seem to cause problems...

So probably the check should be in ub960_rxport_config_eq(). With a
FIXME comment, and a short note where it fails.

That said, if everyone (?) agrees that the HW should support this, it
would be really nice if you can keep poking the FPD-Link people in TI
and try to get clarification on what's going on (what's the diff between
ub960 and ub954).

Btw, did you look at the other EQ related writes, and check if they're
valid for ub954?

 Tomi

>>>       clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>>>       data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>>>   @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct
>>> ub960_data *priv)
>>>       if (priv->hw_data->is_ub9702)
>>>           ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>>>                    NULL);
>>> +    else if (priv->hw_data->is_ub954) {
>>> +        /* From DS90UB954-Q1 datasheet:
>>> +         * "REFCLK_FREQ measurement is not synchronized. Value in this
>>> +         * register should read twice and only considered valid if
>>> +         * REFCLK_FREQ is unchanged between reads."
>>> +         */
>>> +        unsigned long timeout = jiffies + msecs_to_jiffies(100);
>>> +
>>> +        do {
>>> +            u8 refclk_new;
>>> +
>>> +            ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
>>> +                     NULL);
>>> +            if (ret)
>>> +                goto err_pd_gpio;
>>> +
>>> +            if (refclk_new == refclk_freq)
>>> +                break;
>>> +            refclk_freq = refclk_new;
>>> +        } while (time_before(jiffies, timeout));
>>> +    }
>>
>> This feels a bit too much for a not-that-important debug print... As the
>> tests show that a single read is (practically always?) enough, I think
>> we can just use the same code as for ub960. Maybe add a comment about
>> it, though.
>>
> 
> okay, I will use the same code that is being used for UB960 and will add
> a comment
> about that.
> 
> Thanks and Regards,
> Abhilash Chandra
> 
> [1]: https://gist.github.com/Yemike-Abhilash-Chandra/
> c6b3da2a10586567a3a4179a2b20d21b
> 
>>   Tomi
>>
>>>       else
>>>           ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>>>                    NULL);
>>> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client
>>> *client)
>>>       mutex_destroy(&priv->reg_lock);
>>>   }
>>>   +static const struct ub960_hw_data ds90ub954_hw = {
>>> +    .model = "ub954",
>>> +    .num_rxports = 2,
>>> +    .num_txports = 1,
>>> +    .is_ub954 = true,
>>> +};
>>> +
>>>   static const struct ub960_hw_data ds90ub960_hw = {
>>>       .model = "ub960",
>>>       .num_rxports = 4,
>>> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw
>>> = {
>>>   };
>>>     static const struct i2c_device_id ub960_id[] = {
>>> +    { "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>>>       { "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>>>       { "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>>>       {}
>>> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>>>   MODULE_DEVICE_TABLE(i2c, ub960_id);
>>>     static const struct of_device_id ub960_dt_ids[] = {
>>> +    { .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>>>       { .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>>>       { .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>>>       {}
>>

Re: [PATCH 2/2] media: i2c: ds90ub960: Add support for DS90UB954-Q1

[Yemike Abhilash Chandra]

Hi Tomi,
Thanks for the review.

On 02/06/25 12:46, Tomi Valkeinen wrote:
> Hi,
> 
> On 28/05/2025 09:25, Yemike Abhilash Chandra wrote:
>> Hi Tomi,
>>
>> Thanks for the review.
>>
>> On 27/05/25 11:10, Tomi Valkeinen wrote:
>>> Hi,
>>>
>>> On 23/05/2025 11:36, Yemike Abhilash Chandra wrote:
>>>> DS90UB954-Q1 is an FPDLink-III deserializer that is mostly register
>>>> compatible with DS90UB960-Q1. The main difference is that it supports
>>>> half of the RX and TX ports, i.e. 2x FPDLink RX ports and 1x CSI TX
>>>> port.
>>>>
>>>> Some other registers are marked as reserved in the datasheet as well,
>>>> notably around CSI-TX frame and line-count monitoring and some other
>>>
>>> Hmm what does that mean? That in log_status we show random data (or
>>> maybe always 0) for these?
>>>
>>
>> It seems like it is showing 0's for these. I streamed around 100 frames.
>> But the frame counter and line counter returned is 0. Please find the
>> logs at [1].
> 
> If the registers are marked as reserved and don't function, we should
> not use them. Here it doesn't do any harm when running the code, but it
> does decrease the usefulness of log_status if the user is shown data
> that is wrong (and the user most likely doesn't know it's wrong).
> 

Yes, Understood. I will address this in the next revision.

>>>> status registers. The datasheet also does not mention anything about
>>>> setting strobe position, and fails to lock the RX ports if we forcefully
>>>> set it, so disable it through the hw_data.
>>>
>>> This app-note has some details:
>>>
>>> https://www.ti.com/lit/an/snla301/snla301.pdf
>>>
>>>> Link: https://www.ti.com/lit/gpn/ds90ub954-q1
>>>> Signed-off-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>>>> ---
>>>>    drivers/media/i2c/Kconfig     |  2 +-
>>>>    drivers/media/i2c/ds90ub960.c | 46 +++++++++++++++++++++++++++++++++++
>>>>    2 files changed, 47 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>>>> index e68202954a8f..6e265e1cec20 100644
>>>> --- a/drivers/media/i2c/Kconfig
>>>> +++ b/drivers/media/i2c/Kconfig
>>>> @@ -1662,7 +1662,7 @@ config VIDEO_DS90UB960
>>>>        select V4L2_FWNODE
>>>>        select VIDEO_V4L2_SUBDEV_API
>>>>        help
>>>> -      Device driver for the Texas Instruments DS90UB960
>>>> +      Device driver for the Texas Instruments DS90UB954/DS90UB960
>>>>          FPD-Link III Deserializer and DS90UB9702 FPD-Link IV
>>>> Deserializer.
>>>>      config VIDEO_MAX96714
>>>> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/
>>>> ds90ub960.c
>>>> index ed2cf9d247d1..38e4f006d098 100644
>>>> --- a/drivers/media/i2c/ds90ub960.c
>>>> +++ b/drivers/media/i2c/ds90ub960.c
>>>> @@ -460,6 +460,7 @@ struct ub960_hw_data {
>>>>        u8 num_txports;
>>>>        bool is_ub9702;
>>>>        bool is_fpdlink4;
>>>> +    bool is_ub954;
>>>
>>> No, let's not add any more of these. We should have enums for the device
>>> model and the "family" (ub954/ub960 are clearly of the same family,
>>> whereas ub9702 is of a newer one).
>>>
>>
>> Got it. I will add enums in the next revision.
>>
>>>>    };
>>>>      enum ub960_rxport_mode {
>>>> @@ -982,6 +983,10 @@ static int ub960_txport_select(struct ub960_data
>>>> *priv, u8 nport)
>>>>          lockdep_assert_held(&priv->reg_lock);
>>>>    +    /* TX port registers are shared for UB954*/
>>>
>>> Space missing at the end. What does the comment mean? "registers are
>>> shared"?
>>>
>>
>> Apologies for the inaccurate comment description, My intention to
>> comment that the tx_port_select function does not make sense for
>> UB954, since we have only 1 CSI TX. May be I can have something
>> like below.
>>
>> /** UB954 has only 1 CSI TX. Hence, no need to select **/
>>
>>> I think it's good to have this after the lockdep assert. The lock rules
>>> are in place, even if on ub954 we don't do anything here.
>>>
>>>> +    if (priv->hw_data->is_ub954)
>>>> +        return 0;
>>>> +
>>>>        if (priv->reg_current.txport == nport)
>>>>            return 0;
>>>>    @@ -1415,6 +1420,13 @@ static int ub960_parse_dt_txport(struct
>>>> ub960_data *priv,
>>>>            goto err_free_vep;
>>>>        }
>>>>    +    /* UB954 does not support 1.2 Gbps */
>>>> +    if (priv->tx_data_rate == MHZ(1200) && priv->hw_data->is_ub954) {
>>>
>>> Test for ub954 first, 1200 MHz second. It's more logical for the reader
>>> that way.
>>>
>>
>> Noted, will do that in the next revision.
>>
>>>> +        dev_err(dev, "tx%u: invalid 'link-frequencies' value\n",
>>>> nport);
>>>> +        ret = -EINVAL;
>>>> +        goto err_free_vep;
>>>> +    }
>>>> +
>>>>        v4l2_fwnode_endpoint_free(&vep);
>>>>          priv->txports[nport] = txport;
>>>> @@ -1572,6 +1584,10 @@ static int ub960_rxport_set_strobe_pos(struct
>>>> ub960_data *priv,
>>>>        u8 clk_delay, data_delay;
>>>>        int ret = 0;
>>>>    +    /* FIXME: After writing to this area the UB954 chip no longer
>>>> responds */
>>>> +    if (priv->hw_data->is_ub954)
>>>> +        return 0;
>>>> +
>>>
>>> Check the app note. It would be nice to have this working, as, afaik,
>>> the HW functionality should be the same on ub954 and ub960.
>>>
>>
>> I tried referring the app note and changed the strobe position values
>> accordingly, but it did not help.
>>
>> Since the app note also specifies the below at Table 2 Strobe Adaption
>> Modes
>>
>> "
>> AEQ Adaption Mode--> Strobe position is selected as part of AEQ. This is
>> the default mode.
>>
>> Manual Adaption Mode --> The strobe position is selected manually and
>> will remain at
>> the specified position until a new one is chosen. This mode is
>> recommended as an
>> evaluation and debugging mode "
>>
>> Since, under the default settings, the strobe position is selected as
>> part of the AEQ process.
>> Can we limit the ub960_rxport_set_strobe_pos function to only UB960 and
>> UB9702.
> 
> Ok. But it doesn't sound good if we just skip the
> ub960_rxport_set_strobe_pos(), but keep all the other EQ related writes.
> I.e. we do the EQ config partially, and leave out parts that, for
> unknown reasons, seem to cause problems...
> 
> So probably the check should be in ub960_rxport_config_eq(). With a
> FIXME comment, and a short note where it fails.
> 
> That said, if everyone (?) agrees that the HW should support this, it
> would be really nice if you can keep poking the FPD-Link people in TI
> and try to get clarification on what's going on (what's the diff between
> ub960 and ub954).
> 

Yes, I will do that.

> Btw, did you look at the other EQ related writes, and check if they're
> valid for ub954?
> 

Not until now, will check that.

Thanks and Regards
Abhilash Chandra


>   Tomi
> 
>>>>        clk_delay = UB960_IR_RX_ANA_STROBE_SET_CLK_NO_EXTRA_DELAY;
>>>>        data_delay = UB960_IR_RX_ANA_STROBE_SET_DATA_NO_EXTRA_DELAY;
>>>>    @@ -5021,6 +5037,27 @@ static int ub960_enable_core_hw(struct
>>>> ub960_data *priv)
>>>>        if (priv->hw_data->is_ub9702)
>>>>            ret = ub960_read(priv, UB9702_SR_REFCLK_FREQ, &refclk_freq,
>>>>                     NULL);
>>>> +    else if (priv->hw_data->is_ub954) {
>>>> +        /* From DS90UB954-Q1 datasheet:
>>>> +         * "REFCLK_FREQ measurement is not synchronized. Value in this
>>>> +         * register should read twice and only considered valid if
>>>> +         * REFCLK_FREQ is unchanged between reads."
>>>> +         */
>>>> +        unsigned long timeout = jiffies + msecs_to_jiffies(100);
>>>> +
>>>> +        do {
>>>> +            u8 refclk_new;
>>>> +
>>>> +            ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_new,
>>>> +                     NULL);
>>>> +            if (ret)
>>>> +                goto err_pd_gpio;
>>>> +
>>>> +            if (refclk_new == refclk_freq)
>>>> +                break;
>>>> +            refclk_freq = refclk_new;
>>>> +        } while (time_before(jiffies, timeout));
>>>> +    }
>>>
>>> This feels a bit too much for a not-that-important debug print... As the
>>> tests show that a single read is (practically always?) enough, I think
>>> we can just use the same code as for ub960. Maybe add a comment about
>>> it, though.
>>>
>>
>> okay, I will use the same code that is being used for UB960 and will add
>> a comment
>> about that.
>>
>> Thanks and Regards,
>> Abhilash Chandra
>>
>> [1]: https://gist.github.com/Yemike-Abhilash-Chandra/
>> c6b3da2a10586567a3a4179a2b20d21b
>>
>>>    Tomi
>>>
>>>>        else
>>>>            ret = ub960_read(priv, UB960_XR_REFCLK_FREQ, &refclk_freq,
>>>>                     NULL);
>>>> @@ -5177,6 +5214,13 @@ static void ub960_remove(struct i2c_client
>>>> *client)
>>>>        mutex_destroy(&priv->reg_lock);
>>>>    }
>>>>    +static const struct ub960_hw_data ds90ub954_hw = {
>>>> +    .model = "ub954",
>>>> +    .num_rxports = 2,
>>>> +    .num_txports = 1,
>>>> +    .is_ub954 = true,
>>>> +};
>>>> +
>>>>    static const struct ub960_hw_data ds90ub960_hw = {
>>>>        .model = "ub960",
>>>>        .num_rxports = 4,
>>>> @@ -5192,6 +5236,7 @@ static const struct ub960_hw_data ds90ub9702_hw
>>>> = {
>>>>    };
>>>>      static const struct i2c_device_id ub960_id[] = {
>>>> +    { "ds90ub954-q1", (kernel_ulong_t)&ds90ub954_hw },
>>>>        { "ds90ub960-q1", (kernel_ulong_t)&ds90ub960_hw },
>>>>        { "ds90ub9702-q1", (kernel_ulong_t)&ds90ub9702_hw },
>>>>        {}
>>>> @@ -5199,6 +5244,7 @@ static const struct i2c_device_id ub960_id[] = {
>>>>    MODULE_DEVICE_TABLE(i2c, ub960_id);
>>>>      static const struct of_device_id ub960_dt_ids[] = {
>>>> +    { .compatible = "ti,ds90ub954-q1", .data = &ds90ub954_hw },
>>>>        { .compatible = "ti,ds90ub960-q1", .data = &ds90ub960_hw },
>>>>        { .compatible = "ti,ds90ub9702-q1", .data = &ds90ub9702_hw },
>>>>        {}
>>>
>