Hi Raphael,
Thanks for the patch.
Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Le 21/08/2025 à 13:08, Raphael Gallais-Pou a écrit :
> From: Yannick Fertre <yannick.fertre@foss.st.com>
>
> Handle LVDS pixel clock.
>
> The LTDC operates with multiple clock domains for register access,
> requiring all clocks to be provided during read/write operations. This
> imposes a dependency between the LVDS and LTDC to access correctly all
> LTDC registers. And because both IPs' pixel rates must be synchronized,
> the LTDC has to handle the LVDS clock.
>
> Signed-off-by: Yannick Fertre <yannick.fertre@foss.st.com>
> Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
> ---
> drivers/gpu/drm/stm/ltdc.c | 22 +++++++++++++++++++++-
> drivers/gpu/drm/stm/ltdc.h | 1 +
> 2 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 17548dd3484a0a3e1015c58c752b80f8892a0ff7..f84a9a8590f0653e422798ff61804d7c3966caef 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -837,6 +837,12 @@ ltdc_crtc_mode_valid(struct drm_crtc *crtc,
> int target_max = target + CLK_TOLERANCE_HZ;
> int result;
>
> + if (ldev->lvds_clk) {
> + result = clk_round_rate(ldev->lvds_clk, target);
> + drm_dbg_driver(crtc->dev, "lvds pixclk rate target %d, available %d\n",
> + target, result);
> + }
> +
> result = clk_round_rate(ldev->pixel_clk, target);
>
> DRM_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result);
> @@ -1878,6 +1884,8 @@ void ltdc_suspend(struct drm_device *ddev)
> clk_disable_unprepare(ldev->pixel_clk);
> if (ldev->bus_clk)
> clk_disable_unprepare(ldev->bus_clk);
> + if (ldev->lvds_clk)
> + clk_disable_unprepare(ldev->lvds_clk);
> }
>
> int ltdc_resume(struct drm_device *ddev)
> @@ -1895,8 +1903,16 @@ int ltdc_resume(struct drm_device *ddev)
>
> if (ldev->bus_clk) {
> ret = clk_prepare_enable(ldev->bus_clk);
> - if (ret)
> + if (ret) {
> drm_err(ddev, "failed to enable bus clock (%d)\n", ret);
> + return ret;
> + }
> + }
> +
> + if (ldev->lvds_clk) {
> + ret = clk_prepare_enable(ldev->lvds_clk);
> + if (ret)
> + drm_err(ddev, "failed to prepare lvds clock\n");
> }
>
> return ret;
> @@ -1981,6 +1997,10 @@ int ltdc_load(struct drm_device *ddev)
> }
> }
>
> + ldev->lvds_clk = devm_clk_get(dev, "lvds");
> + if (IS_ERR(ldev->lvds_clk))
> + ldev->lvds_clk = NULL;
> +
> rstc = devm_reset_control_get_exclusive(dev, NULL);
>
> mutex_init(&ldev->err_lock);
> diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
> index ddfa8ae61a7ba5dc446fae647562d0ec8e6953e1..17b51a7ce28eee5de6d24ca943ca3b1f48695dfd 100644
> --- a/drivers/gpu/drm/stm/ltdc.h
> +++ b/drivers/gpu/drm/stm/ltdc.h
> @@ -48,6 +48,7 @@ struct ltdc_device {
> void __iomem *regs;
> struct regmap *regmap;
> struct clk *pixel_clk; /* lcd pixel clock */
> + struct clk *lvds_clk; /* lvds pixel clock */
> struct clk *bus_clk; /* bus clock */
> struct mutex err_lock; /* protecting error_status */
> struct ltdc_caps caps;
>