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SubjectRe: [PATCH] drm/stm: ltdc: filter mode pixel clock vs pad constraint
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Hi Yannick,

On 06/29/2018 01:22 PM, Yannick Fertre wrote:
> Filter the requested mode pixel clock frequency according
> to the pad maximum supported frequency.
>
> Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
> ---
> drivers/gpu/drm/stm/ltdc.c | 16 ++++++++++++----
> drivers/gpu/drm/stm/ltdc.h | 1 +
> 2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 00e3262..96d20c2 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -491,6 +491,14 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,
> int target_max = target + CLK_TOLERANCE_HZ;
> int result;
>
> + result = clk_round_rate(ldev->pixel_clk, target);
> +
> + DRM_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result);
> +
> + /* Filter modes according to the max frequency supported by the pads */
> + if (result > ldev->caps.pad_max_freq_hz)
> + return MODE_CLOCK_HIGH;
> +
> /*
> * Accept all "preferred" modes:
> * - this is important for panels because panel clock tolerances are
> @@ -502,10 +510,6 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,
> if (mode->type & DRM_MODE_TYPE_PREFERRED)
> return MODE_OK;
>
> - result = clk_round_rate(ldev->pixel_clk, target);
> -
> - DRM_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result);
> -
> /*
> * Filter modes according to the clock value, particularly useful for
> * hdmi modes that require precise pixel clocks.
> @@ -1039,11 +1043,15 @@ static int ltdc_get_caps(struct drm_device *ddev)
> * does not work on 2nd layer.
> */
> ldev->caps.non_alpha_only_l1 = true;
> + ldev->caps.pad_max_freq_hz = 90000000;
> + if (ldev->caps.hw_version == HWVER_10200)
> + ldev->caps.pad_max_freq_hz = 65000000;
> break;
> case HWVER_20101:
> ldev->caps.reg_ofs = REG_OFS_4;
> ldev->caps.pix_fmt_hw = ltdc_pix_fmt_a1;
> ldev->caps.non_alpha_only_l1 = false;
> + ldev->caps.pad_max_freq_hz = 150000000;
> break;
> default:
> return -ENODEV;
> diff --git a/drivers/gpu/drm/stm/ltdc.h b/drivers/gpu/drm/stm/ltdc.h
> index c14e4db..0294d38 100644
> --- a/drivers/gpu/drm/stm/ltdc.h
> +++ b/drivers/gpu/drm/stm/ltdc.h
> @@ -20,6 +20,7 @@ struct ltdc_caps {
> u32 bus_width; /* bus width (32 or 64 bits) */
> const u32 *pix_fmt_hw; /* supported pixel formats */
> bool non_alpha_only_l1; /* non-native no-alpha formats on layer 1 */
> + int pad_max_freq_hz; /* max frequency supported by pad */

Thank you for your patch,

Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Tested-by: Philippe Cornu <philippe.cornu@st.com>

Philippe :-)

> };
>
> #define LTDC_MAX_LAYER 4
>
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