[PATCH 0/2] drm/mipi-dsi: support LPM (Low Power Mode) transfer

[PATCH 0/2] drm/mipi-dsi: support LPM (Low Power Mode) transfer

[Inki Dae]

This patch series adds LPM tranfer support for video and command data.

For this, this patch adds two flags, and makes MIPI DSI host to send
commands to LCD Panel device with LPM if mode_flags of LCD Panel driver
includes LPM flag.

And also it applies this feature to Exynos MIPI DSI driver.

Inki Dae (2):
  drm/mipi-dsi: add (LPM) Low Power Mode transfer support
  drm/exynos: dsi: add LPM (Low Power Mode) transfer support

 drivers/gpu/drm/drm_mipi_dsi.c          |    3 +++
 drivers/gpu/drm/exynos/exynos_drm_dsi.c |   22 ++++++++++++++++++++--
 include/drm/drm_mipi_dsi.h              |    4 ++++
 3 files changed, 27 insertions(+), 2 deletions(-)

-- 
1.7.9.5

[PATCH 1/2] drm/mipi-dsi: add (LPM) Low Power Mode transfer support

[Inki Dae]

This patch adds below two flags for LPM transfer, and it attaches LPM flags
to a msg in accordance with master's mode_flags set by LCD Panel driver.

MIPI_DSI_MODE_CMD_LPM: low power command transfer
MIPI_DSI_MODE_VIDEO_LPM: low power video transfer

MIPI DSI spec says,
     "the host processor controls the desired mode of clock operation.
      Host protocol and applications control Clock Lane operating mode
      (High Speed or Low Power mode). System designers are responsible
      for understanding the clock requirements for peripherals attached
      to DSI and controlling clock behavior in accordance with those
      requirements."

Some LCD Panel devices, nt35502a, would need LPM transfer support
because they should receive some initial commands with LPM by default
hardware setting.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/gpu/drm/drm_mipi_dsi.c |    3 +++
 include/drm/drm_mipi_dsi.h     |    4 ++++
 2 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index e633df2..6b2bbda 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -232,6 +232,9 @@ int mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, unsigned int channel,
 		break;
 	}
 
+	if (dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM)
+		msg.flags = MIPI_DSI_MSG_USE_LPM;
+
 	return ops->transfer(dsi->host, &msg);
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_write);
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 944f33f..1c41e49 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -94,6 +94,10 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
 #define MIPI_DSI_MODE_VSYNC_FLUSH	BIT(8)
 /* disable EoT packets in HS mode */
 #define MIPI_DSI_MODE_EOT_PACKET	BIT(9)
+/* command low power mode */
+#define MIPI_DSI_MODE_CMD_LPM		BIT(10)
+/* video low power mode */
+#define MIPI_DSI_MODE_VIDEO_LPM		BIT(11)
 
 enum mipi_dsi_pixel_format {
 	MIPI_DSI_FMT_RGB888,
-- 
1.7.9.5

Re: [PATCH 1/2] drm/mipi-dsi: add (LPM) Low Power Mode transfer support

[Andrzej Hajda]

Hi Inki,

+CC: Thierry and Alexandre

On 07/18/2014 12:56 PM, Inki Dae wrote:
> This patch adds below two flags for LPM transfer, and it attaches LPM flags
> to a msg in accordance with master's mode_flags set by LCD Panel driver.
>
> MIPI_DSI_MODE_CMD_LPM: low power command transfer
> MIPI_DSI_MODE_VIDEO_LPM: low power video transfer
What is the difference between these two?
Why not just MIPI_DSI_MODE_LPM combined optionally with
MIPI_DSI_MODE_VIDEO ?
Anyway as I understand the only role of this flag is to always trigger
MIPI_DSI_MSG_USE_LPM flag in DSI message. Maybe better is to check both
flags in DSI host, using some helper function.

>
> MIPI DSI spec says,
>      "the host processor controls the desired mode of clock operation.
>       Host protocol and applications control Clock Lane operating mode
>       (High Speed or Low Power mode). System designers are responsible
>       for understanding the clock requirements for peripherals attached
>       to DSI and controlling clock behavior in accordance with those
>       requirements."
>
> Some LCD Panel devices, nt35502a, would need LPM transfer support
> because they should receive some initial commands with LPM by default
> hardware setting.

It would be good to see usage of this flag in the driver. Is it possible
to post it?

I have posted few months ago TC358764 driver[1] which also uses LPM for
initialization, have you look at it.

[1]:
http://lists.freedesktop.org/archives/dri-devel/2014-February/053713.html

Regards
Andrzej

>
> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/gpu/drm/drm_mipi_dsi.c |    3 +++
>  include/drm/drm_mipi_dsi.h     |    4 ++++
>  2 files changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index e633df2..6b2bbda 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -232,6 +232,9 @@ int mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, unsigned int channel,
>  		break;
>  	}
>  
> +	if (dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM)
> +		msg.flags = MIPI_DSI_MSG_USE_LPM;
> +
>  	return ops->transfer(dsi->host, &msg);
>  }
>  EXPORT_SYMBOL(mipi_dsi_dcs_write);
> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
> index 944f33f..1c41e49 100644
> --- a/include/drm/drm_mipi_dsi.h
> +++ b/include/drm/drm_mipi_dsi.h
> @@ -94,6 +94,10 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
>  #define MIPI_DSI_MODE_VSYNC_FLUSH	BIT(8)
>  /* disable EoT packets in HS mode */
>  #define MIPI_DSI_MODE_EOT_PACKET	BIT(9)
> +/* command low power mode */
> +#define MIPI_DSI_MODE_CMD_LPM		BIT(10)
> +/* video low power mode */
> +#define MIPI_DSI_MODE_VIDEO_LPM		BIT(11)
>  
>  enum mipi_dsi_pixel_format {
>  	MIPI_DSI_FMT_RGB888,

Re: [PATCH 1/2] drm/mipi-dsi: add (LPM) Low Power Mode transfer support

[Inki Dae]

On 2014년 07월 24일 19:23, Andrzej Hajda wrote:
> Hi Inki,
> 
> +CC: Thierry and Alexandre
> 
> On 07/18/2014 12:56 PM, Inki Dae wrote:
>> This patch adds below two flags for LPM transfer, and it attaches LPM flags
>> to a msg in accordance with master's mode_flags set by LCD Panel driver.
>>
>> MIPI_DSI_MODE_CMD_LPM: low power command transfer
>> MIPI_DSI_MODE_VIDEO_LPM: low power video transfer
> What is the difference between these two?

They mean that MIPI DSI controller have to transfer command or video to
Panel in Low Power Mode according to these flags.

> Why not just MIPI_DSI_MODE_LPM combined optionally with
> MIPI_DSI_MODE_VIDEO ?
> Anyway as I understand the only role of this flag is to always trigger
> MIPI_DSI_MSG_USE_LPM flag in DSI message. Maybe better is to check both
> flags in DSI host, using some helper function.

No any flag would mean that video and command data have to be
transferred in HS mode. On the other hands, if there is one of above
flags, the data would be transferred in Low Power Mode. So I think
separated flags, MIPI_DSI_MODE_VIDEO/COMMAND and MIPI_DSI_MODE_LPM
causes unnecessary flag combination.

> 
>>
>> MIPI DSI spec says,
>>      "the host processor controls the desired mode of clock operation.
>>       Host protocol and applications control Clock Lane operating mode
>>       (High Speed or Low Power mode). System designers are responsible
>>       for understanding the clock requirements for peripherals attached
>>       to DSI and controlling clock behavior in accordance with those
>>       requirements."
>>
>> Some LCD Panel devices, nt35502a, would need LPM transfer support
>> because they should receive some initial commands with LPM by default
>> hardware setting.
> 
> It would be good to see usage of this flag in the driver. Is it possible
> to post it?

Yes, but that driver is needed for more cleanup works. Anyway I will
post it in the near future.
> 
> I have posted few months ago TC358764 driver[1] which also uses LPM for
> initialization, have you look at it.
> 
> [1]:
> http://lists.freedesktop.org/archives/dri-devel/2014-February/053713.html
> 
> Regards
> Andrzej
> 
>>
>> Signed-off-by: Inki Dae <inki.dae@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>> ---
>>  drivers/gpu/drm/drm_mipi_dsi.c |    3 +++
>>  include/drm/drm_mipi_dsi.h     |    4 ++++
>>  2 files changed, 7 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
>> index e633df2..6b2bbda 100644
>> --- a/drivers/gpu/drm/drm_mipi_dsi.c
>> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
>> @@ -232,6 +232,9 @@ int mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, unsigned int channel,
>>  		break;
>>  	}
>>  
>> +	if (dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM)
>> +		msg.flags = MIPI_DSI_MSG_USE_LPM;
>> +
>>  	return ops->transfer(dsi->host, &msg);
>>  }
>>  EXPORT_SYMBOL(mipi_dsi_dcs_write);
>> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
>> index 944f33f..1c41e49 100644
>> --- a/include/drm/drm_mipi_dsi.h
>> +++ b/include/drm/drm_mipi_dsi.h
>> @@ -94,6 +94,10 @@ void mipi_dsi_host_unregister(struct mipi_dsi_host *host);
>>  #define MIPI_DSI_MODE_VSYNC_FLUSH	BIT(8)
>>  /* disable EoT packets in HS mode */
>>  #define MIPI_DSI_MODE_EOT_PACKET	BIT(9)
>> +/* command low power mode */
>> +#define MIPI_DSI_MODE_CMD_LPM		BIT(10)
>> +/* video low power mode */
>> +#define MIPI_DSI_MODE_VIDEO_LPM		BIT(11)
>>  
>>  enum mipi_dsi_pixel_format {
>>  	MIPI_DSI_FMT_RGB888,
> 
> 

[PATCH 2/2] drm/exynos: dsi: add LPM (Low Power Mode) transfer support

[Inki Dae]

This patch adds LPM transfer support for video or command data.

With this patch, Exynos MIPI DSI controller can transfer command or
video data with HS or LP mode in accordance with mode_flags set
by LCD Panel driver.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_dsi.c |   22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 2df3592..b120554 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -426,13 +426,28 @@ static int exynos_dsi_enable_clock(struct exynos_dsi *dsi)
 			| DSIM_ESC_PRESCALER(esc_div)
 			| DSIM_LANE_ESC_CLK_EN_CLK
 			| DSIM_LANE_ESC_CLK_EN_DATA(BIT(dsi->lanes) - 1)
-			| DSIM_BYTE_CLK_SRC(0)
-			| DSIM_TX_REQUEST_HSCLK;
+			| DSIM_BYTE_CLK_SRC(0);
+
+	if (!(dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM))
+		reg |= DSIM_TX_REQUEST_HSCLK;
+
 	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
 
 	return 0;
 }
 
+static void exynos_dsi_enable_hs_clock(struct exynos_dsi *dsi,
+					bool enable)
+{
+	u32 reg = readl(dsi->reg_base + DSIM_CLKCTRL_REG);
+
+	reg &= ~DSIM_TX_REQUEST_HSCLK;
+	if (enable)
+		reg |= DSIM_TX_REQUEST_HSCLK;
+
+	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
+}
+
 static void exynos_dsi_disable_clock(struct exynos_dsi *dsi)
 {
 	u32 reg;
@@ -575,6 +590,9 @@ static void exynos_dsi_set_display_enable(struct exynos_dsi *dsi, bool enable)
 {
 	u32 reg;
 
+	if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_LPM))
+		exynos_dsi_enable_hs_clock(dsi, true);
+
 	reg = readl(dsi->reg_base + DSIM_MDRESOL_REG);
 	if (enable)
 		reg |= DSIM_MAIN_STAND_BY;
-- 
1.7.9.5

Re: [PATCH 2/2] drm/exynos: dsi: add LPM (Low Power Mode) transfer support

[Andrzej Hajda]

+CC: Thierry and Alexandre

On 07/18/2014 12:56 PM, Inki Dae wrote:
> This patch adds LPM transfer support for video or command data.
>
> With this patch, Exynos MIPI DSI controller can transfer command or
> video data with HS or LP mode in accordance with mode_flags set
> by LCD Panel driver.
>
> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c |   22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 2df3592..b120554 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -426,13 +426,28 @@ static int exynos_dsi_enable_clock(struct exynos_dsi *dsi)
>  			| DSIM_ESC_PRESCALER(esc_div)
>  			| DSIM_LANE_ESC_CLK_EN_CLK
>  			| DSIM_LANE_ESC_CLK_EN_DATA(BIT(dsi->lanes) - 1)
> -			| DSIM_BYTE_CLK_SRC(0)
> -			| DSIM_TX_REQUEST_HSCLK;
> +			| DSIM_BYTE_CLK_SRC(0);
> +
> +	if (!(dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM))
> +		reg |= DSIM_TX_REQUEST_HSCLK;
> +

Maybe I missed sth but it seems to me slightly unrelated to LPM flag.
According to specs some panels can require this clock even in LPM mode.
I wonder if recently introduced  MIPI_DSI_CLOCK_NON_CONTINUOUS wouldn't
handle it.

>  	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
>  
>  	return 0;
>  }
>  
> +static void exynos_dsi_enable_hs_clock(struct exynos_dsi *dsi,
> +					bool enable)
> +{
> +	u32 reg = readl(dsi->reg_base + DSIM_CLKCTRL_REG);
> +
> +	reg &= ~DSIM_TX_REQUEST_HSCLK;
> +	if (enable)
> +		reg |= DSIM_TX_REQUEST_HSCLK;
> +
> +	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
> +}
> +
>  static void exynos_dsi_disable_clock(struct exynos_dsi *dsi)
>  {
>  	u32 reg;
> @@ -575,6 +590,9 @@ static void exynos_dsi_set_display_enable(struct exynos_dsi *dsi, bool enable)
>  {
>  	u32 reg;
>  
> +	if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_LPM))
> +		exynos_dsi_enable_hs_clock(dsi, true);
> +

It does not care about enable argument of the function, I guess it should.

Regards
Andrzej

>  	reg = readl(dsi->reg_base + DSIM_MDRESOL_REG);
>  	if (enable)
>  		reg |= DSIM_MAIN_STAND_BY;

Re: [PATCH 2/2] drm/exynos: dsi: add LPM (Low Power Mode) transfer support

[Inki Dae]

On 2014년 07월 24일 19:48, Andrzej Hajda wrote:
> +CC: Thierry and Alexandre
> 
> On 07/18/2014 12:56 PM, Inki Dae wrote:
>> This patch adds LPM transfer support for video or command data.
>>
>> With this patch, Exynos MIPI DSI controller can transfer command or
>> video data with HS or LP mode in accordance with mode_flags set
>> by LCD Panel driver.
>>
>> Signed-off-by: Inki Dae <inki.dae@samsung.com>
>> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
>> ---
>>  drivers/gpu/drm/exynos/exynos_drm_dsi.c |   22 ++++++++++++++++++++--
>>  1 file changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
>> index 2df3592..b120554 100644
>> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
>> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
>> @@ -426,13 +426,28 @@ static int exynos_dsi_enable_clock(struct exynos_dsi *dsi)
>>  			| DSIM_ESC_PRESCALER(esc_div)
>>  			| DSIM_LANE_ESC_CLK_EN_CLK
>>  			| DSIM_LANE_ESC_CLK_EN_DATA(BIT(dsi->lanes) - 1)
>> -			| DSIM_BYTE_CLK_SRC(0)
>> -			| DSIM_TX_REQUEST_HSCLK;
>> +			| DSIM_BYTE_CLK_SRC(0);
>> +
>> +	if (!(dsi->mode_flags & MIPI_DSI_MODE_CMD_LPM))
>> +		reg |= DSIM_TX_REQUEST_HSCLK;
>> +
> 
> Maybe I missed sth but it seems to me slightly unrelated to LPM flag.
> According to specs some panels can require this clock even in LPM mode.
> I wonder if recently introduced  MIPI_DSI_CLOCK_NON_CONTINUOUS wouldn't
> handle it.

It's different. MIPI DSI spec says,
"For continuous clock behaviour, the Clock Lane remains in high-speed
mode generating active clock signals between HS data packet
transmissions. For non-continuous clock behaviour, *the Clock Lane
enters the LP-11 state between HS data packet transmissions*."

> 
>>  	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
>>  
>>  	return 0;
>>  }
>>  
>> +static void exynos_dsi_enable_hs_clock(struct exynos_dsi *dsi,
>> +					bool enable)
>> +{
>> +	u32 reg = readl(dsi->reg_base + DSIM_CLKCTRL_REG);
>> +
>> +	reg &= ~DSIM_TX_REQUEST_HSCLK;
>> +	if (enable)
>> +		reg |= DSIM_TX_REQUEST_HSCLK;
>> +
>> +	writel(reg, dsi->reg_base + DSIM_CLKCTRL_REG);
>> +}
>> +
>>  static void exynos_dsi_disable_clock(struct exynos_dsi *dsi)
>>  {
>>  	u32 reg;
>> @@ -575,6 +590,9 @@ static void exynos_dsi_set_display_enable(struct exynos_dsi *dsi, bool enable)
>>  {
>>  	u32 reg;
>>  
>> +	if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_LPM))
>> +		exynos_dsi_enable_hs_clock(dsi, true);
>> +
> 
> It does not care about enable argument of the function, I guess it should.
> 

Yes, it's better to enable HS clock only in case of enabling. So will
add one more flag like below,

if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_LPM) && enable)

Thank,
Inki Dae

> Regards
> Andrzej
> 
>>  	reg = readl(dsi->reg_base + DSIM_MDRESOL_REG);
>>  	if (enable)
>>  		reg |= DSIM_MAIN_STAND_BY;
> 
> --
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