linux-kernel - [PATCH 1/2] drm/rockchip: Properly adjust to a true clock in adjusted

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Date:   Fri, 14 Jun 2019 15:47:29 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Sandy Huang <hjc@...k-chips.com>, heiko@...ech.de,
        seanpaul@...omium.org
Cc:     linux-rockchip@...ts.infradead.org, urjaman@...il.com,
        Douglas Anderson <dianders@...omium.org>,
        Yakir Yang <ykk@...k-chips.com>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        linux-arm-kernel@...ts.infradead.org,
        Daniel Vetter <daniel@...ll.ch>
Subject: [PATCH 1/2] drm/rockchip: Properly adjust to a true clock in adjusted_mode

When fixing up the clock in vop_crtc_mode_fixup() we're not doing it
quite correctly.  Specifically if we've got the true clock 266666667 Hz,
we'll perform this calculation:
   266666667 / 1000 => 266666

Later when we try to set the clock we'll do clk_set_rate(266666 *
1000).  The common clock framework won't actually pick the proper clock
in this case since it always wants clocks <= the specified one.

Let's solve this by using DIV_ROUND_UP.

Fixes: b59b8de31497 ("drm/rockchip: return a true clock rate to adjusted_mode")
Signed-off-by: Douglas Anderson <dianders@...omium.org>
Signed-off-by: Sean Paul <seanpaul@...omium.org>
Reviewed-by: Yakir Yang <ykk@...k-chips.com>
---
Back in 2016 Mark Yao said he applied this to his drm fixes [1], but it's
2019 and it's still missing so I'm posting again.

[1] https://patchwork.freedesktop.org/patch/103872/

 drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index e4580d8f21e1..d124f34ab9fc 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1006,7 +1006,8 @@ static bool vop_crtc_mode_fixup(struct drm_crtc *crtc,
 	struct vop *vop = to_vop(crtc);
 
 	adjusted_mode->clock =
-		clk_round_rate(vop->dclk, mode->clock * 1000) / 1000;
+		DIV_ROUND_UP(clk_round_rate(vop->dclk, mode->clock * 1000),
+			     1000);
 
 	return true;
 }
-- 
2.22.0.410.gd8fdbe21b5-goog