drm/stm: ltdc: filter mode pixel clock vs pad constraint

Filter the requested mode pixel clock frequency according
to the pad maximum supported frequency.

Signed-off-by: Yannick Fertre <yannick.fertre@st.com>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Tested-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1530271342-5532-1-git-send-email-yannick.fertre@st.com

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index d997a60..f1f3733 100644 (file)
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c
@@ -457,6 +457,14 @@ ltdc_crtc_mode_valid(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
@@ -468,10 +476,6 @@ ltdc_crtc_mode_valid(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.
@@ -991,11 +995,15 @@ 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 1e16d6a..d5afb89 100644 (file)
--- a/drivers/gpu/drm/stm/ltdc.h
+++ b/drivers/gpu/drm/stm/ltdc.h
@@ -18,6 +18,7 @@ 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 */
 };
 
 #define LTDC_MAX_LAYER 4