On Fri, Jun 23, 2023 at 06:07:44PM +0300, Laurent Pinchart wrote:
> Hi Geert,
>
> Thank you for the patch.
>
> On Thu, Jun 22, 2023 at 11:21:18AM +0200, Geert Uytterhoeven wrote:
> > The SH-Mobile LCD Controller is part of a PM Domain on all relevant SoCs
> > (clock domain on all, power domain on some). Hence it may not be
> > sufficient to manage the LCDC module clock explicitly (e.g. if the
> > selected clock source differs from SHMOB_DRM_CLK_BUS).
> >
> > Fix this by using Runtime PM instead.
> >
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c | 11 ++++++++++-
> > drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c | 5 +++++
> > 2 files changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> > index fbfd906844da490c..84dbf35025d7be63 100644
> > --- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> > +++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_crtc.c
> > @@ -9,6 +9,7 @@
> >
> > #include <linux/backlight.h>
> > #include <linux/clk.h>
> > +#include <linux/pm_runtime.h>
> >
> > #include <drm/drm_crtc.h>
> > #include <drm/drm_crtc_helper.h>
> > @@ -170,10 +171,16 @@ static void shmob_drm_crtc_start(struct shmob_drm_crtc *scrtc)
> > if (WARN_ON(format == NULL))
> > return;
> >
> > + ret = pm_runtime_resume_and_get(sdev->dev);
> > + if (ret)
> > + return;
> > +
> > /* Enable clocks before accessing the hardware. */
> > ret = shmob_drm_clk_on(sdev);
>
> This would be best located in the runtime PM resume handler. Same for
> disabling clocks in the runtime PM suspend handler.
The driver should then depend on CONFIG_PM. There's no indirect
dependency through CONFIG_DRM as far as I can tell, but there's one
through ARCH_SHMOBILE. This then got me puzzled, as ARCH_SHMOBILE is
defined in arch/sh/Kconfig, and this driver depends on ARM. Am I missing
something ?
> > - if (ret < 0)
> > + if (ret < 0) {
> > + pm_runtime_put(sdev->dev);
> > return;
> > + }
> >
> > /* Reset and enable the LCDC. */
> > lcdc_write(sdev, LDCNT2R, lcdc_read(sdev, LDCNT2R) | LDCNT2R_BR);
> > @@ -271,6 +278,8 @@ static void shmob_drm_crtc_stop(struct shmob_drm_crtc *scrtc)
> > /* Stop clocks. */
> > shmob_drm_clk_off(sdev);
> >
> > + pm_runtime_put(sdev->dev);
> > +
> > scrtc->started = false;
> > }
> >
> > diff --git a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
> > index 30493ce874192e3e..4f01caa119637032 100644
> > --- a/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
> > +++ b/drivers/gpu/drm/renesas/shmobile/shmob_drm_drv.c
> > @@ -13,6 +13,7 @@
> > #include <linux/module.h>
> > #include <linux/platform_device.h>
> > #include <linux/pm.h>
> > +#include <linux/pm_runtime.h>
> > #include <linux/slab.h>
> >
> > #include <drm/drm_drv.h>
> > @@ -216,6 +217,10 @@ static int shmob_drm_probe(struct platform_device *pdev)
> > if (IS_ERR(sdev->mmio))
> > return PTR_ERR(sdev->mmio);
> >
> > + ret = devm_pm_runtime_enable(&pdev->dev);
> > + if (ret)
> > + return ret;
> > +
>
> I would move this after shmob_drm_setup_clocks(), to ensure that the
> runtime PM suspend and resume handlers will have access to clocks.
>
> > ret = shmob_drm_setup_clocks(sdev, pdata->clk_source);
> > if (ret < 0)
> > return ret;
--
Regards,
Laurent Pinchart
