Re: [PATCH] arm64: dts: imx8mq: Add clock parents for mipi dphy

Hi,
On Sun, Jan 10, 2021 at 08:46:29PM +0800, Shawn Guo wrote:

On Fri, Dec 18, 2020 at 06:50:05PM +0100, Guido Günther wrote:

quoted

This makes sure the clock tree setup for the dphy is not dependent on
other components.

Without this change bringing up the display can fail like

  kernel: phy phy-30a00300.dphy.2: Invalid CM/CN/CO values: 165/217/1
  kernel: phy phy-30a00300.dphy.2: for hs_clk/ref_clk=451656000/593999998 ~ 165/217

if LCDIF doesn't set up that part of the clock tree first. This was
noticed when testing the Librem 5 devkit with defconfig. It doesn't
happen when modules are built in.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
 arch/arm64/boot/dts/freescale/imx8mq.dtsi | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mq.dtsi b/arch/arm64/boot/dts/freescale/imx8mq.dtsi
index a841a023e8e0..ca0847e8f13c 100644
--- a/arch/arm64/boot/dts/freescale/imx8mq.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mq.dtsi

@@ -1016,9 +1016,14 @@ dphy: dphy@30a00300 {
 				reg = <0x30a00300 0x100>;
 				clocks = <&clk IMX8MQ_CLK_DSI_PHY_REF>;
 				clock-names = "phy_ref";
-				assigned-clocks = <&clk IMX8MQ_CLK_DSI_PHY_REF>;
-				assigned-clock-parents = <&clk IMX8MQ_VIDEO_PLL1_OUT>;
-				assigned-clock-rates = <24000000>;
+				assigned-clocks = <&clk IMX8MQ_VIDEO_PLL1_REF_SEL>,
+						  <&clk IMX8MQ_VIDEO_PLL1_BYPASS>,
+						  <&clk IMX8MQ_CLK_DSI_PHY_REF>,
+						  <&clk IMX8MQ_VIDEO_PLL1>;

You do not seem to set parent or rate on IMX8MQ_VIDEO_PLL1.  Why do you
have it here?

Good point. I've added a clock rate for IMX8MQ_VIDEO_PLL1 since
then the clock tree reproduces exactly with and with the DSI host
controller disabled in DT (otherwise we end up with a rate of 22MHz
instead of 24Mhz).

Cheers,
 -- Guido

Shawn

quoted

+				assigned-clock-parents = <&clk IMX8MQ_CLK_25M>,
+						  <&clk IMX8MQ_VIDEO_PLL1>,
+						  <&clk IMX8MQ_VIDEO_PLL1_OUT>;
+				assigned-clock-rates = <0>, <0>, <24000000>;
 				#phy-cells = <0>;
 				power-domains = <&pgc_mipi>;
 				status = "disabled";
-- 
2.29.2

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel