On 04/25/2018 09:12 AM, Yannick FERTRE wrote:
> Hi Philippe,
>
> Reviewed-by: Yannick Fertré <yannick.fertre@xxxxxx>
>
Applied on drm-misc-next.
Many thanks,
Philippe :-)
> On 04/17/2018 01:40 PM, Philippe Cornu wrote:
>> Add mode_valid() function to filter modes according to available
>> pll clock values and "preferred" modes. It is particularly
>> useful for hdmi modes that require precise pixel clocks.
>>
>> Note that "preferred" modes are always accepted:
>> - this is important for panels because panel clock tolerances are
>> bigger than hdmi ones and there is no reason to not accept them
>> (the fps may vary a little but it is not a problem).
>> - the hdmi preferred mode will be accepted too, but userland will
>> be able to use others hdmi "valid" modes if necessary.
>>
>> Signed-off-by: Philippe Cornu <philippe.cornu@xxxxxx>
>> ---
>> drivers/gpu/drm/stm/ltdc.c | 38 ++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 38 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
>> index 014cef8cef37..616191fe98ae 100644
>> --- a/drivers/gpu/drm/stm/ltdc.c
>> +++ b/drivers/gpu/drm/stm/ltdc.c
>> @@ -445,6 +445,43 @@ static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,
>> reg_set(ldev->regs, LTDC_SRCR, SRCR_IMR);
>> }
>>
>> +#define CLK_TOLERANCE_HZ 50
>> +
>> +static enum drm_mode_status
>> +ltdc_crtc_mode_valid(struct drm_crtc *crtc,
>> + const struct drm_display_mode *mode)
>> +{
>> + struct ltdc_device *ldev = crtc_to_ltdc(crtc);
>> + int target = mode->clock * 1000;
>> + int target_min = target - CLK_TOLERANCE_HZ;
>> + int target_max = target + CLK_TOLERANCE_HZ;
>> + int result;
>> +
>> + /*
>> + * Accept all "preferred" modes:
>> + * - this is important for panels because panel clock tolerances are
>> + * bigger than hdmi ones and there is no reason to not accept them
>> + * (the fps may vary a little but it is not a problem).
>> + * - the hdmi preferred mode will be accepted too, but userland will
>> + * be able to use others hdmi "valid" modes if necessary.
>> + */
>> + 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.
>> + */
>> + if (result < target_min || result > target_max)
>> + return MODE_CLOCK_RANGE;
>> +
>> + return MODE_OK;
>> +}
>> +
>> static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
>> const struct drm_display_mode *mode,
>> struct drm_display_mode *adjusted_mode)
>> @@ -559,6 +596,7 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc,
>> }
>>
>> static const struct drm_crtc_helper_funcs ltdc_crtc_helper_funcs = {
>> + .mode_valid = ltdc_crtc_mode_valid,
>> .mode_fixup = ltdc_crtc_mode_fixup,
>> .mode_set_nofb = ltdc_crtc_mode_set_nofb,
>> .atomic_flush = ltdc_crtc_atomic_flush,
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