* [PATCH 2/3] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.
2019-03-01 15:33 [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
@ 2019-03-01 15:33 ` Christoph Muellner
[not found] ` <367bf78a-f079-f0b4-68fe-52c86823c174@fivetechno.de>
2019-03-01 15:33 ` [PATCH 3/3] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma Christoph Muellner
` (3 subsequent siblings)
4 siblings, 1 reply; 17+ messages in thread
From: Christoph Muellner @ 2019-03-01 15:33 UTC (permalink / raw)
To: robh+dt, mark.rutland, heiko, shawn.lin
Cc: devicetree, Jeffy Chen, linux-kernel, Viresh Kumar, Brian Norris,
Douglas Anderson, Vicente Bergas, Kishon Vijay Abraham I,
linux-rockchip, Tony Xie, Klaus Goger, Enric Balletbo i Serra,
Randy Li, Philipp Tomsich, Ezequiel Garcia, linux-arm-kernel,
Christoph Muellner
A previous patch introduced the property 'drive-impedance-ohm'
for the RK3399's emmc phy node. This patch sets this value
explicitly to the default value of 50 Ohm.
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index 6cc1c9fa4ea6..b875364a7709 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -1450,6 +1450,7 @@
clock-names = "refclk";
#phy-cells = <1>;
resets = <&cru SRST_PCIEPHY>;
+ drive-impedance-ohm = <50>;
reset-names = "phy";
status = "disabled";
};
--
2.11.0
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^ permalink raw reply related [flat|nested] 17+ messages in thread* [PATCH 3/3] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma
2019-03-01 15:33 [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
2019-03-01 15:33 ` [PATCH 2/3] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy Christoph Muellner
@ 2019-03-01 15:33 ` Christoph Muellner
2019-03-01 15:59 ` [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Heiko Stuebner
` (2 subsequent siblings)
4 siblings, 0 replies; 17+ messages in thread
From: Christoph Muellner @ 2019-03-01 15:33 UTC (permalink / raw)
To: robh+dt, mark.rutland, heiko, shawn.lin
Cc: devicetree, Matthias Brugger, linux-kernel, Ezequiel Garcia,
Viresh Kumar, Brian Norris, Douglas Anderson, Vicente Bergas,
Kishon Vijay Abraham I, linux-rockchip, Tony Xie, Klaus Goger,
Enric Balletbo i Serra, Randy Li, Philipp Tomsich, Shunqian Zheng,
linux-arm-kernel, Christoph Muellner
The RK3399-Q7 (Puma) requires 33 Ohm drive strength to ensure signal
integrity at HS-400 (200MHz clock, DDR signalling).
A repeated EMC testing run validates that this increase does not
negatively impact EMC compliance (emissions have ample distance to
the regulatory limits).
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
---
arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 0130b9f98c9d..4f75bb6b2f14 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -146,6 +146,7 @@
&emmc_phy {
status = "okay";
+ drive-impedance-ohm = <33>;
};
&gmac {
--
2.11.0
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^ permalink raw reply related [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 15:33 [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
2019-03-01 15:33 ` [PATCH 2/3] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy Christoph Muellner
2019-03-01 15:33 ` [PATCH 3/3] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma Christoph Muellner
@ 2019-03-01 15:59 ` Heiko Stuebner
2019-03-01 16:21 ` Christoph Müllner
2019-03-01 16:48 ` Doug Anderson
2019-03-01 16:51 ` Robin Murphy
4 siblings, 1 reply; 17+ messages in thread
From: Heiko Stuebner @ 2019-03-01 15:59 UTC (permalink / raw)
To: Christoph Muellner
Cc: mark.rutland, devicetree, Matthias Brugger, linux-kernel,
Emil Renner Berthing, Tony Xie, Viresh Kumar, shawn.lin, Randy Li,
Douglas Anderson, Vicente Bergas, Kishon Vijay Abraham I,
linux-rockchip, robh+dt, Klaus Goger, Enric Balletbo i Serra,
Philipp Tomsich, Ezequiel Garcia, linux-arm-kernel
Hi Christoph,
Am Freitag, 1. März 2019, 16:33:43 CET schrieb Christoph Muellner:
> The rockchip-emmc PHY can be configured with different
> drive impedance values. Currenlty a value of 50 Ohm is
> hard coded into the driver.
>
> This patch introduces the DTS property 'drive-impedance-ohm'
> for the rockchip-emmc phy node, which uses the value from the DTS
> to setup the drive impedance accordingly.
>
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> ---
> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
looks good on first glance, but is missing an addition to the emmc-phy
devicetree binding in
Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
Heiko
> 1 file changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
> index 19bf84f0bc67..5413fa73dd45 100644
> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
> unsigned int reg_offset;
> struct regmap *reg_base;
> struct clk *emmcclk;
> + unsigned int drive_impedance;
> };
>
> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
> {
> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>
> - /* Drive impedance: 50 Ohm */
> + /* Drive impedance: from DTS */
> regmap_write(rk_phy->reg_base,
> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
> + HIWORD_UPDATE(rk_phy->drive_impedance,
> PHYCTRL_DR_MASK,
> PHYCTRL_DR_SHIFT));
>
> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
> .owner = THIS_MODULE,
> };
>
> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
> +{
> + switch (dr_ohm) {
> + case 100:
> + return PHYCTRL_DR_100OHM;
> + case 66:
> + return PHYCTRL_DR_66OHM;
> + case 50:
> + return PHYCTRL_DR_50OHM;
> + case 40:
> + return PHYCTRL_DR_40OHM;
> + case 33:
> + return PHYCTRL_DR_33OHM;
> + }
> +
> + dev_warn(&pdev->dev,
> + "Invalid value %u for drive-impedance-ohm. "
> + "Falling back to 50 Ohm.\n",
> + dr_ohm);
> + return PHYCTRL_DR_50OHM;
> +}
> +
> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> struct phy_provider *phy_provider;
> struct regmap *grf;
> unsigned int reg_offset;
> + u32 val;
>
> if (!dev->parent || !dev->parent->of_node)
> return -ENODEV;
> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> rk_phy->reg_offset = reg_offset;
> rk_phy->reg_base = grf;
>
> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
> + dev_info(dev,
> + "Missing drive-impedance-ohm property in node %s "
> + "Falling back to 50 Ohm.\n",
> + dev->of_node->name);
> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
> + } else {
> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
> + }
> +
> generic_phy = devm_phy_create(dev, dev->of_node, &ops);
> if (IS_ERR(generic_phy)) {
> dev_err(dev, "failed to create PHY\n");
>
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^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 15:59 ` [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Heiko Stuebner
@ 2019-03-01 16:21 ` Christoph Müllner
0 siblings, 0 replies; 17+ messages in thread
From: Christoph Müllner @ 2019-03-01 16:21 UTC (permalink / raw)
To: Heiko Stuebner
Cc: mark.rutland, devicetree, Matthias Brugger, linux-kernel,
Emil Renner Berthing, Tony Xie, Viresh Kumar, shawn.lin, Randy Li,
Douglas Anderson, Vicente Bergas, Kishon Vijay Abraham I,
linux-rockchip, robh+dt, Klaus Goger, Enric Balletbo i Serra,
Philipp Tomsich, Ezequiel Garcia, linux-arm-kernel
Hi Heiko,
> On 01.03.2019, at 16:59, Heiko Stuebner <heiko@sntech.de> wrote:
>
> Hi Christoph,
>
> Am Freitag, 1. März 2019, 16:33:43 CET schrieb Christoph Muellner:
>> The rockchip-emmc PHY can be configured with different
>> drive impedance values. Currenlty a value of 50 Ohm is
>> hard coded into the driver.
>>
>> This patch introduces the DTS property 'drive-impedance-ohm'
>> for the rockchip-emmc phy node, which uses the value from the DTS
>> to setup the drive impedance accordingly.
>>
>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> ---
>> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
>
> looks good on first glance, but is missing an addition to the emmc-phy
> devicetree binding in
> Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
you are right.
I've just sent that in a separate patch (DT doc changes need to be in a separate commit anyways).
Thanks,
Christoph
>
>
> Heiko
>
>> 1 file changed, 36 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> index 19bf84f0bc67..5413fa73dd45 100644
>> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
>> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
>> unsigned int reg_offset;
>> struct regmap *reg_base;
>> struct clk *emmcclk;
>> + unsigned int drive_impedance;
>> };
>>
>> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
>> {
>> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>>
>> - /* Drive impedance: 50 Ohm */
>> + /* Drive impedance: from DTS */
>> regmap_write(rk_phy->reg_base,
>> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
>> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
>> + HIWORD_UPDATE(rk_phy->drive_impedance,
>> PHYCTRL_DR_MASK,
>> PHYCTRL_DR_SHIFT));
>>
>> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
>> .owner = THIS_MODULE,
>> };
>>
>> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
>> +{
>> + switch (dr_ohm) {
>> + case 100:
>> + return PHYCTRL_DR_100OHM;
>> + case 66:
>> + return PHYCTRL_DR_66OHM;
>> + case 50:
>> + return PHYCTRL_DR_50OHM;
>> + case 40:
>> + return PHYCTRL_DR_40OHM;
>> + case 33:
>> + return PHYCTRL_DR_33OHM;
>> + }
>> +
>> + dev_warn(&pdev->dev,
>> + "Invalid value %u for drive-impedance-ohm. "
>> + "Falling back to 50 Ohm.\n",
>> + dr_ohm);
>> + return PHYCTRL_DR_50OHM;
>> +}
>> +
>> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> struct phy_provider *phy_provider;
>> struct regmap *grf;
>> unsigned int reg_offset;
>> + u32 val;
>>
>> if (!dev->parent || !dev->parent->of_node)
>> return -ENODEV;
>> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> rk_phy->reg_offset = reg_offset;
>> rk_phy->reg_base = grf;
>>
>> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
>> + dev_info(dev,
>> + "Missing drive-impedance-ohm property in node %s "
>> + "Falling back to 50 Ohm.\n",
>> + dev->of_node->name);
>> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
>> + } else {
>> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
>> + }
>> +
>> generic_phy = devm_phy_create(dev, dev->of_node, &ops);
>> if (IS_ERR(generic_phy)) {
>> dev_err(dev, "failed to create PHY\n");
>>
>
>
>
>
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^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 15:33 [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
` (2 preceding siblings ...)
2019-03-01 15:59 ` [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Heiko Stuebner
@ 2019-03-01 16:48 ` Doug Anderson
2019-03-01 16:59 ` Philipp Tomsich
2019-03-01 18:09 ` Christoph Müllner
2019-03-01 16:51 ` Robin Murphy
4 siblings, 2 replies; 17+ messages in thread
From: Doug Anderson @ 2019-03-01 16:48 UTC (permalink / raw)
To: Christoph Muellner
Cc: Mark Rutland, devicetree, Matthias Brugger, Heiko Stübner,
Tony Xie, Viresh Kumar, Shawn Lin, Randy Li, LKML, Vicente Bergas,
Kishon Vijay Abraham I, open list:ARM/Rockchip SoC...,
Rob Herring, Klaus Goger, Enric Balletbo i Serra, Philipp Tomsich,
Ezequiel Garcia, Linux ARM, Emil Renner Berthing
Hi,
On Fri, Mar 1, 2019 at 7:37 AM Christoph Muellner
<christoph.muellner@theobroma-systems.com> wrote:
>
> The rockchip-emmc PHY can be configured with different
> drive impedance values. Currenlty a value of 50 Ohm is
> hard coded into the driver.
>
> This patch introduces the DTS property 'drive-impedance-ohm'
> for the rockchip-emmc phy node, which uses the value from the DTS
> to setup the drive impedance accordingly.
>
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> ---
> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
> 1 file changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
> index 19bf84f0bc67..5413fa73dd45 100644
> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
> unsigned int reg_offset;
> struct regmap *reg_base;
> struct clk *emmcclk;
> + unsigned int drive_impedance;
> };
>
> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
> {
> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>
> - /* Drive impedance: 50 Ohm */
> + /* Drive impedance: from DTS */
> regmap_write(rk_phy->reg_base,
> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
> + HIWORD_UPDATE(rk_phy->drive_impedance,
> PHYCTRL_DR_MASK,
> PHYCTRL_DR_SHIFT));
>
> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
> .owner = THIS_MODULE,
> };
>
> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
> +{
> + switch (dr_ohm) {
> + case 100:
> + return PHYCTRL_DR_100OHM;
> + case 66:
> + return PHYCTRL_DR_66OHM;
> + case 50:
> + return PHYCTRL_DR_50OHM;
> + case 40:
> + return PHYCTRL_DR_40OHM;
> + case 33:
> + return PHYCTRL_DR_33OHM;
> + }
> +
> + dev_warn(&pdev->dev,
> + "Invalid value %u for drive-impedance-ohm. "
> + "Falling back to 50 Ohm.\n",
> + dr_ohm);
> + return PHYCTRL_DR_50OHM;
> +}
> +
> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> struct phy_provider *phy_provider;
> struct regmap *grf;
> unsigned int reg_offset;
> + u32 val;
>
> if (!dev->parent || !dev->parent->of_node)
> return -ENODEV;
> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> rk_phy->reg_offset = reg_offset;
> rk_phy->reg_base = grf;
>
> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
> + dev_info(dev,
> + "Missing drive-impedance-ohm property in node %s "
> + "Falling back to 50 Ohm.\n",
> + dev->of_node->name);
This is awfully noisy for something that pretty much all existing
boards will run. debug level instead of info level? Also:
* Don't split strings
across lines
* There's a magic % thing to get the name of an OF node. Use that.
> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
> + } else {
> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
> + }
It's been a long time since I looked at this, but I could have sworn
that it was more complicated than that. Specifically I though you
were supposed to query the eMMC card for what it supported and then
resolve that with what the host could support.
Assuming that this is supposed to be queried from the card (which is
how I remember it) then you definitely don't want it in the device
tree since you want to be able to stuff various different eMMC parts
and we should be able to figure out the impedance at runtime.
NOTE: IIRC the old value of 50 ohms is required to be supported by all
hosts and cards and is specified to be the default.
I do see at least the summary of what I thought of this before at
<https://patchwork.kernel.org/patch/9086541/>
(Sorry if the above is wrong and feel free to correct me--I don't have
time at the moment to do all the full research but hopefully you can
dig more based on my pointers. Feel free to call me on my BS)
-Doug
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^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 16:48 ` Doug Anderson
@ 2019-03-01 16:59 ` Philipp Tomsich
2019-03-01 18:09 ` Christoph Müllner
1 sibling, 0 replies; 17+ messages in thread
From: Philipp Tomsich @ 2019-03-01 16:59 UTC (permalink / raw)
To: Doug Anderson
Cc: Mark Rutland, devicetree, Matthias Brugger, Emil Renner Berthing,
Heiko Stübner, Tony Xie, Viresh Kumar, Shawn Lin, Randy Li,
LKML, Vicente Bergas, Kishon Vijay Abraham I,
open list:ARM/Rockchip SoC..., Rob Herring, Klaus Goger,
Enric Balletbo i Serra, Ezequiel Garcia, Linux ARM,
Christoph Muellner
Doug,
> On 01.03.2019, at 17:48, Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Fri, Mar 1, 2019 at 7:37 AM Christoph Muellner
> <christoph.muellner@theobroma-systems.com> wrote:
>>
>> The rockchip-emmc PHY can be configured with different
>> drive impedance values. Currenlty a value of 50 Ohm is
>> hard coded into the driver.
>>
>> This patch introduces the DTS property 'drive-impedance-ohm'
>> for the rockchip-emmc phy node, which uses the value from the DTS
>> to setup the drive impedance accordingly.
>>
>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> ---
>> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
>> 1 file changed, 36 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> index 19bf84f0bc67..5413fa73dd45 100644
>> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
>> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
>> unsigned int reg_offset;
>> struct regmap *reg_base;
>> struct clk *emmcclk;
>> + unsigned int drive_impedance;
>> };
>>
>> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
>> {
>> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>>
>> - /* Drive impedance: 50 Ohm */
>> + /* Drive impedance: from DTS */
>> regmap_write(rk_phy->reg_base,
>> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
>> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
>> + HIWORD_UPDATE(rk_phy->drive_impedance,
>> PHYCTRL_DR_MASK,
>> PHYCTRL_DR_SHIFT));
>>
>> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
>> .owner = THIS_MODULE,
>> };
>>
>> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
>> +{
>> + switch (dr_ohm) {
>> + case 100:
>> + return PHYCTRL_DR_100OHM;
>> + case 66:
>> + return PHYCTRL_DR_66OHM;
>> + case 50:
>> + return PHYCTRL_DR_50OHM;
>> + case 40:
>> + return PHYCTRL_DR_40OHM;
>> + case 33:
>> + return PHYCTRL_DR_33OHM;
>> + }
>> +
>> + dev_warn(&pdev->dev,
>> + "Invalid value %u for drive-impedance-ohm. "
>> + "Falling back to 50 Ohm.\n",
>> + dr_ohm);
>> + return PHYCTRL_DR_50OHM;
>> +}
>> +
>> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> struct phy_provider *phy_provider;
>> struct regmap *grf;
>> unsigned int reg_offset;
>> + u32 val;
>>
>> if (!dev->parent || !dev->parent->of_node)
>> return -ENODEV;
>> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> rk_phy->reg_offset = reg_offset;
>> rk_phy->reg_base = grf;
>>
>> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
>> + dev_info(dev,
>> + "Missing drive-impedance-ohm property in node %s "
>> + "Falling back to 50 Ohm.\n",
>> + dev->of_node->name);
>
> This is awfully noisy for something that pretty much all existing
> boards will run. debug level instead of info level? Also:
>
> * Don't split strings
> across lines
>
> * There's a magic % thing to get the name of an OF node. Use that.
>
>
>> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
>> + } else {
>> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
>> + }
>
> It's been a long time since I looked at this, but I could have sworn
> that it was more complicated than that. Specifically I though you
> were supposed to query the eMMC card for what it supported and then
> resolve that with what the host could support.
>
> Assuming that this is supposed to be queried from the card (which is
> how I remember it) then you definitely don't want it in the device
> tree since you want to be able to stuff various different eMMC parts
> and we should be able to figure out the impedance at runtime.
Not necessarily (i.e. there’s not a bijective relationship, as far as I know):
Higher drive-strenghts allow for faster speeds, but lower drive-strenghts
may have an improved emission profile. For the RK3399-Q7, emissions
with a 33 Ohm preset are ok and we don’t see any reflections.
The chip documentation has the following info:
Impedance Relative Remark
50 Ohm x1 Default driver type, supports up to 200MHz operation
33 Ohm x1.5 Supports up to 200MHz operation
66 Ohm x0.75 The weakest driver that supports up to 200MHz operation.
100 Ohm x0.5 For Low noise and low EMI systems, Minimum operating frequency is system dependent.
40 Ohm x1.2 Supports up to DDR 200MHz operation.
> NOTE: IIRC the old value of 50 ohms is required to be supported by all
> hosts and cards and is specified to be the default.
For our board, we have a series resistor in the line (originally a precaution against
emissions and the BIOS_DISABLE circuitry) — do there’s more dampening on the
signal than on the reference design.
> I do see at least the summary of what I thought of this before at
> <https://patchwork.kernel.org/patch/9086541/>
>
>
> (Sorry if the above is wrong and feel free to correct me--I don't have
> time at the moment to do all the full research but hopefully you can
> dig more based on my pointers. Feel free to call me on my BS)
>
>
> -Doug
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 16:48 ` Doug Anderson
2019-03-01 16:59 ` Philipp Tomsich
@ 2019-03-01 18:09 ` Christoph Müllner
2019-03-01 18:41 ` Philipp Tomsich
1 sibling, 1 reply; 17+ messages in thread
From: Christoph Müllner @ 2019-03-01 18:09 UTC (permalink / raw)
To: Doug Anderson
Cc: Mark Rutland, devicetree, Matthias Brugger, Heiko Stübner,
Tony Xie, Viresh Kumar, Shawn Lin, Randy Li, LKML, Vicente Bergas,
Kishon Vijay Abraham I, open list:ARM/Rockchip SoC...,
Rob Herring, Klaus Goger, Enric Balletbo i Serra, Philipp Tomsich,
Ezequiel Garcia, Linux ARM, Emil Renner Berthing
Hi Doug,
> On 01.03.2019, at 17:48, Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Fri, Mar 1, 2019 at 7:37 AM Christoph Muellner
> <christoph.muellner@theobroma-systems.com> wrote:
>>
>> The rockchip-emmc PHY can be configured with different
>> drive impedance values. Currenlty a value of 50 Ohm is
>> hard coded into the driver.
>>
>> This patch introduces the DTS property 'drive-impedance-ohm'
>> for the rockchip-emmc phy node, which uses the value from the DTS
>> to setup the drive impedance accordingly.
>>
>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> ---
>> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
>> 1 file changed, 36 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> index 19bf84f0bc67..5413fa73dd45 100644
>> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
>> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
>> unsigned int reg_offset;
>> struct regmap *reg_base;
>> struct clk *emmcclk;
>> + unsigned int drive_impedance;
>> };
>>
>> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
>> {
>> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>>
>> - /* Drive impedance: 50 Ohm */
>> + /* Drive impedance: from DTS */
>> regmap_write(rk_phy->reg_base,
>> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
>> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
>> + HIWORD_UPDATE(rk_phy->drive_impedance,
>> PHYCTRL_DR_MASK,
>> PHYCTRL_DR_SHIFT));
>>
>> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
>> .owner = THIS_MODULE,
>> };
>>
>> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
>> +{
>> + switch (dr_ohm) {
>> + case 100:
>> + return PHYCTRL_DR_100OHM;
>> + case 66:
>> + return PHYCTRL_DR_66OHM;
>> + case 50:
>> + return PHYCTRL_DR_50OHM;
>> + case 40:
>> + return PHYCTRL_DR_40OHM;
>> + case 33:
>> + return PHYCTRL_DR_33OHM;
>> + }
>> +
>> + dev_warn(&pdev->dev,
>> + "Invalid value %u for drive-impedance-ohm. "
>> + "Falling back to 50 Ohm.\n",
>> + dr_ohm);
>> + return PHYCTRL_DR_50OHM;
>> +}
>> +
>> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> struct phy_provider *phy_provider;
>> struct regmap *grf;
>> unsigned int reg_offset;
>> + u32 val;
>>
>> if (!dev->parent || !dev->parent->of_node)
>> return -ENODEV;
>> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> rk_phy->reg_offset = reg_offset;
>> rk_phy->reg_base = grf;
>>
>> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
>> + dev_info(dev,
>> + "Missing drive-impedance-ohm property in node %s "
>> + "Falling back to 50 Ohm.\n",
>> + dev->of_node->name);
>
> This is awfully noisy for something that pretty much all existing
> boards will run. debug level instead of info level? Also:
Removed for v2 as suggested by Robin.
>
> * Don't split strings
> across lines
>
> * There's a magic % thing to get the name of an OF node. Use that.
>
>
>> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
>> + } else {
>> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
>> + }
>
> It's been a long time since I looked at this, but I could have sworn
> that it was more complicated than that. Specifically I though you
> were supposed to query the eMMC card for what it supported and then
> resolve that with what the host could support.
>
> Assuming that this is supposed to be queried from the card (which is
> how I remember it) then you definitely don't want it in the device
> tree since you want to be able to stuff various different eMMC parts
> and we should be able to figure out the impedance at runtime.
>
>
> NOTE: IIRC the old value of 50 ohms is required to be supported by all
> hosts and cards and is specified to be the default.
>
When using 50 ohms on our board in HS-400 mode (200 MHz), then
we see communication errors. These are cause by additional components
on the clock line, which damp the 200 Mhz signal too much.
We could do the following:
* sdhci.c provides a default implementation to set the drive impedance (in HOST_CONTROL2,
like it is done already now as part of sdhci_set_ios())
* sdhci-of-arasan.c installs an alternative implementation in case of Rockchip's eMMC controller
* the alternative implementation uses a callback to the Rockchip's eMMC phy driver
* the Rockchip eMMC phy driver sets the drive impedance accordingly
But still we would need a mechanism to override this for our board.
And exactly this override mechanism is provided by the patch series.
Thanks,
Christoph
>
> I do see at least the summary of what I thought of this before at
> <https://patchwork.kernel.org/patch/9086541/>
>
>
> (Sorry if the above is wrong and feel free to correct me--I don't have
> time at the moment to do all the full research but hopefully you can
> dig more based on my pointers. Feel free to call me on my BS)
>
>
> -Doug
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 18:09 ` Christoph Müllner
@ 2019-03-01 18:41 ` Philipp Tomsich
0 siblings, 0 replies; 17+ messages in thread
From: Philipp Tomsich @ 2019-03-01 18:41 UTC (permalink / raw)
To: Christoph Müllner
Cc: Mark Rutland, devicetree, Matthias Brugger, LKML,
Heiko Stübner, Tony Xie, Viresh Kumar, Shawn Lin, Randy Li,
Doug Anderson, Vicente Bergas, Kishon Vijay Abraham I,
open list:ARM/Rockchip SoC..., Rob Herring, Klaus Goger,
Enric Balletbo i Serra, Ezequiel Garcia, Linux ARM,
Emil Renner Berthing
> On 01.03.2019, at 19:09, Christoph Müllner <christoph.muellner@theobroma-systems.com> wrote:
>
> Hi Doug,
>
>> On 01.03.2019, at 17:48, Doug Anderson <dianders@chromium.org> wrote:
>>
>> Hi,
>>
>> On Fri, Mar 1, 2019 at 7:37 AM Christoph Muellner
>> <christoph.muellner@theobroma-systems.com> wrote:
>>>
>>> The rockchip-emmc PHY can be configured with different
>>> drive impedance values. Currenlty a value of 50 Ohm is
>>> hard coded into the driver.
>>>
>>> This patch introduces the DTS property 'drive-impedance-ohm'
>>> for the rockchip-emmc phy node, which uses the value from the DTS
>>> to setup the drive impedance accordingly.
>>>
>>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>>> ---
>>> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
>>> 1 file changed, 36 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
>>> index 19bf84f0bc67..5413fa73dd45 100644
>>> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
>>> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
>>> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
>>> unsigned int reg_offset;
>>> struct regmap *reg_base;
>>> struct clk *emmcclk;
>>> + unsigned int drive_impedance;
>>> };
>>>
>>> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>>> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
>>> {
>>> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>>>
>>> - /* Drive impedance: 50 Ohm */
>>> + /* Drive impedance: from DTS */
>>> regmap_write(rk_phy->reg_base,
>>> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
>>> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
>>> + HIWORD_UPDATE(rk_phy->drive_impedance,
>>> PHYCTRL_DR_MASK,
>>> PHYCTRL_DR_SHIFT));
>>>
>>> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
>>> .owner = THIS_MODULE,
>>> };
>>>
>>> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
>>> +{
>>> + switch (dr_ohm) {
>>> + case 100:
>>> + return PHYCTRL_DR_100OHM;
>>> + case 66:
>>> + return PHYCTRL_DR_66OHM;
>>> + case 50:
>>> + return PHYCTRL_DR_50OHM;
>>> + case 40:
>>> + return PHYCTRL_DR_40OHM;
>>> + case 33:
>>> + return PHYCTRL_DR_33OHM;
>>> + }
>>> +
>>> + dev_warn(&pdev->dev,
>>> + "Invalid value %u for drive-impedance-ohm. "
>>> + "Falling back to 50 Ohm.\n",
>>> + dr_ohm);
>>> + return PHYCTRL_DR_50OHM;
>>> +}
>>> +
>>> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>>> {
>>> struct device *dev = &pdev->dev;
>>> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>>> struct phy_provider *phy_provider;
>>> struct regmap *grf;
>>> unsigned int reg_offset;
>>> + u32 val;
>>>
>>> if (!dev->parent || !dev->parent->of_node)
>>> return -ENODEV;
>>> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>>> rk_phy->reg_offset = reg_offset;
>>> rk_phy->reg_base = grf;
>>>
>>> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
>>> + dev_info(dev,
>>> + "Missing drive-impedance-ohm property in node %s "
>>> + "Falling back to 50 Ohm.\n",
>>> + dev->of_node->name);
>>
>> This is awfully noisy for something that pretty much all existing
>> boards will run. debug level instead of info level? Also:
>
> Removed for v2 as suggested by Robin.
>
>>
>> * Don't split strings
>> across lines
>>
>> * There's a magic % thing to get the name of an OF node. Use that.
>>
>>
>>> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
>>> + } else {
>>> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
>>> + }
>>
>> It's been a long time since I looked at this, but I could have sworn
>> that it was more complicated than that. Specifically I though you
>> were supposed to query the eMMC card for what it supported and then
>> resolve that with what the host could support.
>>
>> Assuming that this is supposed to be queried from the card (which is
>> how I remember it) then you definitely don't want it in the device
>> tree since you want to be able to stuff various different eMMC parts
>> and we should be able to figure out the impedance at runtime.
>>
>>
>> NOTE: IIRC the old value of 50 ohms is required to be supported by all
>> hosts and cards and is specified to be the default.
>>
>
> When using 50 ohms on our board in HS-400 mode (200 MHz), then
> we see communication errors. These are cause by additional components
> on the clock line, which damp the 200 Mhz signal too much.
>
> We could do the following:
>
> * sdhci.c provides a default implementation to set the drive impedance (in HOST_CONTROL2,
> like it is done already now as part of sdhci_set_ios())
> * sdhci-of-arasan.c installs an alternative implementation in case of Rockchip's eMMC controller
> * the alternative implementation uses a callback to the Rockchip's eMMC phy driver
Generally, I would not make this either-or (I may have been less than clear
in my comments to the internal ticket), but rather teach the sdhci-driver to
always notify the eMMC PHY driver (if there is one) of the change.
For the RK3399’s sdhci implementation, the bits in the HOST_CONTROL2
register are ‘reserved’ and marked R/O, so the current implementation will
not work anyway and the PHY driver needs to be notified of the change in
requested drive-strength.
> * the Rockchip eMMC phy driver sets the drive impedance accordingly
>
> But still we would need a mechanism to override this for our board.
> And exactly this override mechanism is provided by the patch series.
The PHY would then need to determine the proper operation point (or an
mapping from a table) to achieve the requested line characteristic for any
given board. In other words: the DTS for puma would still contain an entry
to allow us to override to 33 Ohm when switching to HS-400.
> Thanks,
> Christoph
>
>>
>> I do see at least the summary of what I thought of this before at
>> <https://patchwork.kernel.org/patch/9086541/>
>>
>>
>> (Sorry if the above is wrong and feel free to correct me--I don't have
>> time at the moment to do all the full research but hopefully you can
>> dig more based on my pointers. Feel free to call me on my BS)
>>
>>
>> -Doug
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 15:33 [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
` (3 preceding siblings ...)
2019-03-01 16:48 ` Doug Anderson
@ 2019-03-01 16:51 ` Robin Murphy
2019-03-01 17:38 ` Christoph Müllner
4 siblings, 1 reply; 17+ messages in thread
From: Robin Murphy @ 2019-03-01 16:51 UTC (permalink / raw)
To: Christoph Muellner, robh+dt, mark.rutland, heiko, shawn.lin
Cc: devicetree, Matthias Brugger, Emil Renner Berthing, Viresh Kumar,
Randy Li, linux-kernel, Vicente Bergas, Douglas Anderson,
linux-rockchip, Tony Xie, Klaus Goger, Enric Balletbo i Serra,
Philipp Tomsich, Kishon Vijay Abraham I, Ezequiel Garcia,
linux-arm-kernel
On 01/03/2019 15:33, Christoph Muellner wrote:
> The rockchip-emmc PHY can be configured with different
> drive impedance values. Currenlty a value of 50 Ohm is
> hard coded into the driver.
>
> This patch introduces the DTS property 'drive-impedance-ohm'
> for the rockchip-emmc phy node, which uses the value from the DTS
> to setup the drive impedance accordingly.
>
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> ---
> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
> 1 file changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
> index 19bf84f0bc67..5413fa73dd45 100644
> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
> unsigned int reg_offset;
> struct regmap *reg_base;
> struct clk *emmcclk;
> + unsigned int drive_impedance;
> };
>
> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
> {
> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>
> - /* Drive impedance: 50 Ohm */
> + /* Drive impedance: from DTS */
> regmap_write(rk_phy->reg_base,
> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
> + HIWORD_UPDATE(rk_phy->drive_impedance,
> PHYCTRL_DR_MASK,
> PHYCTRL_DR_SHIFT));
>
> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
> .owner = THIS_MODULE,
> };
>
> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
> +{
> + switch (dr_ohm) {
> + case 100:
> + return PHYCTRL_DR_100OHM;
> + case 66:
> + return PHYCTRL_DR_66OHM;
> + case 50:
> + return PHYCTRL_DR_50OHM;
> + case 40:
> + return PHYCTRL_DR_40OHM;
> + case 33:
> + return PHYCTRL_DR_33OHM;
> + }
> +
> + dev_warn(&pdev->dev,
> + "Invalid value %u for drive-impedance-ohm. "
> + "Falling back to 50 Ohm.\n",
> + dr_ohm);
> + return PHYCTRL_DR_50OHM;
> +}
> +
> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> struct phy_provider *phy_provider;
> struct regmap *grf;
> unsigned int reg_offset;
> + u32 val;
>
> if (!dev->parent || !dev->parent->of_node)
> return -ENODEV;
> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
> rk_phy->reg_offset = reg_offset;
> rk_phy->reg_base = grf;
>
> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
> + dev_info(dev,
> + "Missing drive-impedance-ohm property in node %s "
> + "Falling back to 50 Ohm.\n",
> + dev->of_node->name);
I think we're aiming to use %pOF for node names now, but here it looks
redundant anyway - dev_info() will already show the device name, which
for an of_platform device is the same thing.
> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
> + } else {
> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
> + }
FWIW, if you initialise val to the default (i.e. 50) then you could get
rid of the "else" case and just do the conversion unconditionally.
That's a fairly common idiom for reading optional properties.
Robin.
> +
> generic_phy = devm_phy_create(dev, dev->of_node, &ops);
> if (IS_ERR(generic_phy)) {
> dev_err(dev, "failed to create PHY\n");
>
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^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
2019-03-01 16:51 ` Robin Murphy
@ 2019-03-01 17:38 ` Christoph Müllner
0 siblings, 0 replies; 17+ messages in thread
From: Christoph Müllner @ 2019-03-01 17:38 UTC (permalink / raw)
To: Robin Murphy
Cc: mark.rutland, devicetree, Matthias Brugger, heiko, Tony Xie,
Viresh Kumar, shawn.lin, Randy Li, linux-kernel, Vicente Bergas,
Douglas Anderson, linux-rockchip, robh+dt, Klaus Goger,
Enric Balletbo i Serra, Philipp Tomsich, Kishon Vijay Abraham I,
Ezequiel Garcia, linux-arm-kernel, Emil Renner Berthing
Hi Robin,
> On 01.03.2019, at 17:51, Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 01/03/2019 15:33, Christoph Muellner wrote:
>> The rockchip-emmc PHY can be configured with different
>> drive impedance values. Currenlty a value of 50 Ohm is
>> hard coded into the driver.
>> This patch introduces the DTS property 'drive-impedance-ohm'
>> for the rockchip-emmc phy node, which uses the value from the DTS
>> to setup the drive impedance accordingly.
>> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
>> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> ---
>> drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++--
>> 1 file changed, 36 insertions(+), 2 deletions(-)
>> diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> index 19bf84f0bc67..5413fa73dd45 100644
>> --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
>> +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
>> @@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
>> unsigned int reg_offset;
>> struct regmap *reg_base;
>> struct clk *emmcclk;
>> + unsigned int drive_impedance;
>> };
>> static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
>> @@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
>> {
>> struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
>> - /* Drive impedance: 50 Ohm */
>> + /* Drive impedance: from DTS */
>> regmap_write(rk_phy->reg_base,
>> rk_phy->reg_offset + GRF_EMMCPHY_CON6,
>> - HIWORD_UPDATE(PHYCTRL_DR_50OHM,
>> + HIWORD_UPDATE(rk_phy->drive_impedance,
>> PHYCTRL_DR_MASK,
>> PHYCTRL_DR_SHIFT));
>> @@ -314,6 +315,28 @@ static const struct phy_ops ops = {
>> .owner = THIS_MODULE,
>> };
>> +static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
>> +{
>> + switch (dr_ohm) {
>> + case 100:
>> + return PHYCTRL_DR_100OHM;
>> + case 66:
>> + return PHYCTRL_DR_66OHM;
>> + case 50:
>> + return PHYCTRL_DR_50OHM;
>> + case 40:
>> + return PHYCTRL_DR_40OHM;
>> + case 33:
>> + return PHYCTRL_DR_33OHM;
>> + }
>> +
>> + dev_warn(&pdev->dev,
>> + "Invalid value %u for drive-impedance-ohm. "
>> + "Falling back to 50 Ohm.\n",
>> + dr_ohm);
>> + return PHYCTRL_DR_50OHM;
>> +}
>> +
>> static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> @@ -322,6 +345,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> struct phy_provider *phy_provider;
>> struct regmap *grf;
>> unsigned int reg_offset;
>> + u32 val;
>> if (!dev->parent || !dev->parent->of_node)
>> return -ENODEV;
>> @@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
>> rk_phy->reg_offset = reg_offset;
>> rk_phy->reg_base = grf;
>> + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) {
>> + dev_info(dev,
>> + "Missing drive-impedance-ohm property in node %s "
>> + "Falling back to 50 Ohm.\n",
>> + dev->of_node->name);
>
> I think we're aiming to use %pOF for node names now, but here it looks redundant anyway - dev_info() will already show the device name, which for an of_platform device is the same thing.
>
>> + rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
>> + } else {
>> + rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
>> + }
>
> FWIW, if you initialise val to the default (i.e. 50) then you could get rid of the "else" case and just do the conversion unconditionally. That's a fairly common idiom for reading optional properties.
Ack. For v2 I've removed the else case (not defined value).
Thanks,
Christoph
>
> Robin.
>
>> +
>> generic_phy = devm_phy_create(dev, dev->of_node, &ops);
>> if (IS_ERR(generic_phy)) {
>> dev_err(dev, "failed to create PHY\n");
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