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path: root/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
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Diffstat (limited to 'drivers/gpu/drm/rockchip/rockchip_drm_vop.c')
-rw-r--r--drivers/gpu/drm/rockchip/rockchip_drm_vop.c26
1 files changed, 12 insertions, 14 deletions
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index b28ea5d6a3e2..3e8d9e2d1b67 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1176,26 +1176,24 @@ static bool vop_crtc_mode_fixup(struct drm_crtc *crtc,
*
* Action plan:
*
- * 1. When DRM gives us a mode, we should add 999 Hz to it. That way
- * if the clock we need is 60000001 Hz (~60 MHz) and DRM tells us to
- * make 60000 kHz then the clock framework will actually give us
- * the right clock.
+ * 1. Try to set the exact rate first, and confirm the clock framework
+ * can provide it.
*
- * NOTE: if the PLL (maybe through a divider) could actually make
- * a clock rate 999 Hz higher instead of the one we want then this
- * could be a problem. Unfortunately there's not much we can do
- * since it's baked into DRM to use kHz. It shouldn't matter in
- * practice since Rockchip PLLs are controlled by tables and
- * even if there is a divider in the middle I wouldn't expect PLL
- * rates in the table that are just a few kHz different.
+ * 2. If the clock framework cannot provide the exact rate, we should
+ * add 999 Hz to the requested rate. That way if the clock we need
+ * is 60000001 Hz (~60 MHz) and DRM tells us to make 60000 kHz then
+ * the clock framework will actually give us the right clock.
*
- * 2. Get the clock framework to round the rate for us to tell us
+ * 3. Get the clock framework to round the rate for us to tell us
* what it will actually make.
*
- * 3. Store the rounded up rate so that we don't need to worry about
+ * 4. Store the rounded up rate so that we don't need to worry about
* this in the actual clk_set_rate().
*/
- rate = clk_round_rate(vop->dclk, adjusted_mode->clock * 1000 + 999);
+ rate = clk_round_rate(vop->dclk, adjusted_mode->clock * 1000);
+ if (rate / 1000 != adjusted_mode->clock)
+ rate = clk_round_rate(vop->dclk,
+ adjusted_mode->clock * 1000 + 999);
adjusted_mode->clock = DIV_ROUND_UP(rate, 1000);
return true;