Re: [PATCH] drm/stm: ltdc: filter mode pixel clock vs pad constraint

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