drm/pl111: Support variants with broken clock divider

The early Integrator CLCD synthesized in the Integrator CP and
IM-PD1 FPGAs are broken: their clock dividers do not work
properly. Support disabling the clock divider and drive the
clock directly from the parent under these circumstances.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180206093540.8147-3-linus.walleij@linaro.org

diff --git a/drivers/gpu/drm/pl111/pl111_display.c b/drivers/gpu/drm/pl111/pl111_display.c
index 55ada00..4d4e38b 100644 (file)
--- a/drivers/gpu/drm/pl111/pl111_display.c
+++ b/drivers/gpu/drm/pl111/pl111_display.c
@@ -138,6 +138,9 @@ static void pl111_display_enable(struct drm_simple_display_pipe *pipe,
        tim2 = readl(priv->regs + CLCD_TIM2);
        tim2 &= (TIM2_BCD | TIM2_PCD_LO_MASK | TIM2_PCD_HI_MASK);
 
+       if (priv->variant->broken_clockdivider)
+               tim2 |= TIM2_BCD;
+
        if (mode->flags & DRM_MODE_FLAG_NHSYNC)
                tim2 |= TIM2_IHS;
 
@@ -455,6 +458,11 @@ pl111_init_clock_divider(struct drm_device *drm)
                dev_err(drm->dev, "CLCD: unable to get clcdclk.\n");
                return PTR_ERR(parent);
        }
+       /* If the clock divider is broken, use the parent directly */
+       if (priv->variant->broken_clockdivider) {
+               priv->clk = parent;
+               return 0;
+       }
        parent_name = __clk_get_name(parent);
 
        spin_lock_init(&priv->tim2_lock);

diff --git a/drivers/gpu/drm/pl111/pl111_drm.h b/drivers/gpu/drm/pl111/pl111_drm.h
index bc04b54..a9b1819 100644 (file)
--- a/drivers/gpu/drm/pl111/pl111_drm.h
+++ b/drivers/gpu/drm/pl111/pl111_drm.h
@@ -38,6 +38,8 @@ struct drm_minor;
  * @is_pl110: this is the early PL110 variant
  * @external_bgr: this is the Versatile Pl110 variant with external
  *     BGR/RGB routing
+ * @broken_clockdivider: the clock divider is broken and we need to
+ *     use the supplied clock directly
  * @formats: array of supported pixel formats on this variant
  * @nformats: the length of the array of supported pixel formats
  */
@@ -45,6 +47,7 @@ struct pl111_variant_data {
        const char *name;
        bool is_pl110;
        bool external_bgr;
+       bool broken_clockdivider;
        const u32 *formats;
        unsigned int nformats;
 };

diff --git a/drivers/gpu/drm/pl111/pl111_versatile.c b/drivers/gpu/drm/pl111/pl111_versatile.c
index 1fe8251..4b0a548 100644 (file)
--- a/drivers/gpu/drm/pl111/pl111_versatile.c
+++ b/drivers/gpu/drm/pl111/pl111_versatile.c
@@ -237,6 +237,7 @@ static const u32 pl110_versatile_pixel_formats[] = {
 static const struct pl111_variant_data pl110_integrator = {
        .name = "PL110 Integrator",
        .is_pl110 = true,
+       .broken_clockdivider = true,
        .formats = pl110_integrator_pixel_formats,
        .nformats = ARRAY_SIZE(pl110_integrator_pixel_formats),
 };