Re: [PATCH] drm/msm/dsi: Implement qcom,dsi-phy-regulator-ldo-mode for 28nm PHY

2019-10-21 Thread Stephan Gerhold 
On Mon, Oct 21, 2019 at 01:47:19PM -0400, Sean Paul wrote:
> On Mon, Oct 21, 2019 at 06:34:25PM +0200, Stephan Gerhold wrote:
> > The DSI PHY regulator supports two regulator modes: LDO and DCDC.
> > This mode can be selected using the "qcom,dsi-phy-regulator-ldo-mode"
> > device tree property.
> > 
> > However, at the moment only the 20nm PHY driver actually implements
> > that option. Add a check in the 28nm PHY driver to program the
> > registers correctly for LDO mode.
> > 
> > Tested-by: Nikita Travkin  # l8150
> > Signed-off-by: Stephan Gerhold 
> > ---
> > This is needed to make the display work on Longcheer L8150,
> > which has recently gained mainline support in:
> > https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/commit/?id=16e8e8072108426029f0c16dff7fbe77fae3df8f
> > 
> > This patch is based on code from the downstream kernel:
> > https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/drivers/video/msm/mdss/msm_mdss_io_8974.c?h=LA.BR.1.2.9.1-02310-8x16.0#n152
> > 
> > The LDO regulator configuration is taken from msm8916-qrd.dtsi:
> > https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/arch/arm/boot/dts/qcom/msm8916-qrd.dtsi?h=LA.BR.1.2.9.1-02310-8x16.0#n56
> > ---
> >  drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c | 22 --
> >  1 file changed, 20 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c 
> > b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> > index b3f678f6c2aa..4579e6de4532 100644
> > --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> > +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> > @@ -48,6 +48,25 @@ static void dsi_28nm_phy_regulator_ctrl(struct 
> > msm_dsi_phy *phy, bool enable)
> > return;
> > }
> >  
> > +   if (phy->regulator_ldo_mode) {
> > +   u32 ldo_ctrl;
> > +
> > +   if (phy->cfg->type == MSM_DSI_PHY_28NM_LP)
> > +   ldo_ctrl = 0x05;
> > +   else
> > +   ldo_ctrl = 0x0d;
> > +
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_0, 0x0);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CAL_PWR_CFG, 0);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_5, 0x7);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_3, 0);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_2, 0x1);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_1, 0x1);
> > +   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_4, 0x20);
> > +   dsi_phy_write(phy->base + REG_DSI_28nm_PHY_LDO_CNTRL, ldo_ctrl);
> > +   return;
> > +   }
> 
> nit: Since this has minimal overlap with DCDC mode, I think it would read 
> better
> if you split this into 2 functions:
> dsi_28nm_phy_regulator_enable_dcdc() and dsi_28nm_phy_regulator_enable_ldo()
> 
> So regulator_ctrl would look like:
> 
> static void dsi_28nm_phy_regulator_ctrl(struct msm_dsi_phy *phy, bool enable)
> {
>   void __iomem *base = phy->reg_base;
> 
>   if (!enable) {
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CAL_PWR_CFG, 0);
>   return;
>   }
> 
>   if (phy->regulator_ldo_mode)
> dsi_28nm_phy_regulator_enable_ldo()
> else
> dsi_28nm_phy_regulator_enable_dcdc()
> }
> 

I implemented it similar to dsi_phy_20nm.c [1], which looks like:

static void dsi_20nm_phy_regulator_ctrl(struct msm_dsi_phy *phy, bool enable)
{
void __iomem *base = phy->reg_base;

if (!enable) {
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CAL_PWR_CFG, 0);
return;
}

if (phy->regulator_ldo_mode) {
dsi_phy_write(phy->base + REG_DSI_20nm_PHY_LDO_CNTRL, 0x1d);
return;
}

/* non LDO mode */
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CTRL_1, 0x03);
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CTRL_2, 0x03);
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CTRL_3, 0x00);
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CTRL_4, 0x20);
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CAL_PWR_CFG, 0x01);
dsi_phy_write(phy->base + REG_DSI_20nm_PHY_LDO_CNTRL, 0x00);
dsi_phy_write(base + REG_DSI_20nm_PHY_REGULATOR_CTRL_0, 0x03);
}

I guess it looks better for the 20nm PHY driver since it writes only a
single register in LDO mode rather than the full regulator
configuration.

I'll update my patch and send a v2. Thanks for the suggestion!

[1]: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/msm/dsi/phy/dsi_phy_20nm.c#n42
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Re: [PATCH] drm/msm/dsi: Implement qcom,dsi-phy-regulator-ldo-mode for 28nm PHY

2019-10-21 Thread Sean Paul 
On Mon, Oct 21, 2019 at 06:34:25PM +0200, Stephan Gerhold wrote:
> The DSI PHY regulator supports two regulator modes: LDO and DCDC.
> This mode can be selected using the "qcom,dsi-phy-regulator-ldo-mode"
> device tree property.
> 
> However, at the moment only the 20nm PHY driver actually implements
> that option. Add a check in the 28nm PHY driver to program the
> registers correctly for LDO mode.
> 
> Tested-by: Nikita Travkin  # l8150
> Signed-off-by: Stephan Gerhold 
> ---
> This is needed to make the display work on Longcheer L8150,
> which has recently gained mainline support in:
> https://git.kernel.org/pub/scm/linux/kernel/git/qcom/linux.git/commit/?id=16e8e8072108426029f0c16dff7fbe77fae3df8f
> 
> This patch is based on code from the downstream kernel:
> https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/drivers/video/msm/mdss/msm_mdss_io_8974.c?h=LA.BR.1.2.9.1-02310-8x16.0#n152
> 
> The LDO regulator configuration is taken from msm8916-qrd.dtsi:
> https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/arch/arm/boot/dts/qcom/msm8916-qrd.dtsi?h=LA.BR.1.2.9.1-02310-8x16.0#n56
> ---
>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c | 22 --
>  1 file changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c 
> b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> index b3f678f6c2aa..4579e6de4532 100644
> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_28nm.c
> @@ -48,6 +48,25 @@ static void dsi_28nm_phy_regulator_ctrl(struct msm_dsi_phy 
> *phy, bool enable)
>   return;
>   }
>  
> + if (phy->regulator_ldo_mode) {
> + u32 ldo_ctrl;
> +
> + if (phy->cfg->type == MSM_DSI_PHY_28NM_LP)
> + ldo_ctrl = 0x05;
> + else
> + ldo_ctrl = 0x0d;
> +
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_0, 0x0);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CAL_PWR_CFG, 0);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_5, 0x7);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_3, 0);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_2, 0x1);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_1, 0x1);
> + dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_4, 0x20);
> + dsi_phy_write(phy->base + REG_DSI_28nm_PHY_LDO_CNTRL, ldo_ctrl);
> + return;
> + }

nit: Since this has minimal overlap with DCDC mode, I think it would read better
if you split this into 2 functions:
dsi_28nm_phy_regulator_enable_dcdc() and dsi_28nm_phy_regulator_enable_ldo()

So regulator_ctrl would look like:

static void dsi_28nm_phy_regulator_ctrl(struct msm_dsi_phy *phy, bool enable)
{
void __iomem *base = phy->reg_base;

if (!enable) {
dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CAL_PWR_CFG, 0);
return;
}

if (phy->regulator_ldo_mode)
dsi_28nm_phy_regulator_enable_ldo()
else
dsi_28nm_phy_regulator_enable_dcdc()
}


> +
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_0, 0x0);
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CAL_PWR_CFG, 1);
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_5, 0);
> @@ -56,6 +75,7 @@ static void dsi_28nm_phy_regulator_ctrl(struct msm_dsi_phy 
> *phy, bool enable)
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_1, 0x9);
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_0, 0x7);
>   dsi_phy_write(base + REG_DSI_28nm_PHY_REGULATOR_CTRL_4, 0x20);
> + dsi_phy_write(phy->base + REG_DSI_28nm_PHY_LDO_CNTRL, 0x00);
>  }
>  
>  static int dsi_28nm_phy_enable(struct msm_dsi_phy *phy, int src_pll_id,
> @@ -77,8 +97,6 @@ static int dsi_28nm_phy_enable(struct msm_dsi_phy *phy, int 
> src_pll_id,
>  
>   dsi_28nm_phy_regulator_ctrl(phy, true);
>  
> - dsi_phy_write(base + REG_DSI_28nm_PHY_LDO_CNTRL, 0x00);
> -
>   dsi_28nm_dphy_set_timing(phy, timing);
>  
>   dsi_phy_write(base + REG_DSI_28nm_PHY_CTRL_1, 0x00);
> -- 
> 2.23.0
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS