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[2/2] phy: mediatek: hdmi: mt8195: fix wrong pll calculus

Message ID 20230413-fixes-for-mt8195-hdmi-phy-v1-2-b8482458df0d@baylibre.com
State Superseded
Headers show
Series Fix mtk-hdmi-mt8195 unitialized variable usage and clock rate calculation | expand

Commit Message

Guillaume Ranquet April 13, 2023, 12:46 p.m. UTC
The clock rate calculus in mtk_hdmi_pll_calc() was wrong when it has
been replaced by 'div_u64'.

Fix the issue by multiplying the values in the denominator instead of
dividing them.

Fixes: 45810d486bb44 ("phy: mediatek: add support for phy-mtk-hdmi-mt8195")
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
---
 drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

AngeloGioacchino Del Regno April 14, 2023, 10:34 a.m. UTC | #1
Il 13/04/23 14:46, Guillaume Ranquet ha scritto:
> The clock rate calculus in mtk_hdmi_pll_calc() was wrong when it has
> been replaced by 'div_u64'.
> 
> Fix the issue by multiplying the values in the denominator instead of
> dividing them.
> 
> Fixes: 45810d486bb44 ("phy: mediatek: add support for phy-mtk-hdmi-mt8195")
> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> ---
>   drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> index e10da6c4147e..5e84b294a43e 100644
> --- a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> +++ b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> @@ -271,7 +271,7 @@ static int mtk_hdmi_pll_calc(struct mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
>   	 * [32,24] 9bit integer, [23,0]:24bit fraction
>   	 */
>   	pcw = div_u64(((u64)ns_hdmipll_ck) << PCW_DECIMAL_WIDTH,
> -		      da_hdmitx21_ref_ck / PLL_FBKDIV_HS3);
> +		      da_hdmitx21_ref_ck * PLL_FBKDIV_HS3);

How did that even work?!?!?!? Because ... it worked, I did test it. Bah!
Luck was on your side :-P

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
diff mbox series

Patch

diff --git a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
index e10da6c4147e..5e84b294a43e 100644
--- a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
+++ b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
@@ -271,7 +271,7 @@  static int mtk_hdmi_pll_calc(struct mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
 	 * [32,24] 9bit integer, [23,0]:24bit fraction
 	 */
 	pcw = div_u64(((u64)ns_hdmipll_ck) << PCW_DECIMAL_WIDTH,
-		      da_hdmitx21_ref_ck / PLL_FBKDIV_HS3);
+		      da_hdmitx21_ref_ck * PLL_FBKDIV_HS3);
 
 	if (pcw > GENMASK_ULL(32, 0))
 		return -EINVAL;
@@ -288,7 +288,7 @@  static int mtk_hdmi_pll_calc(struct mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
 	posdiv2 = 1;
 
 	/* Digital clk divider, max /32 */
-	digital_div = div_u64((u64)ns_hdmipll_ck, posdiv1 / posdiv2 / pixel_clk);
+	digital_div = div_u64(ns_hdmipll_ck, posdiv1 * posdiv2 * pixel_clk);
 	if (!(digital_div <= 32 && digital_div >= 1))
 		return -EINVAL;