[PATCH v2] arm64: dts: imx8mp: Align both CSI2 pixel clock

[Alexander Stein]

Am Freitag, 3. Mai 2024, 15:45:57 CEST schrieb Laurent Pinchart:
> On Fri, May 03, 2024 at 02:58:19PM +0200, Alexander Stein wrote:
> > Am Mittwoch, 17. April 2024, 11:12:04 CEST schrieb Alexander Stein:
> > > Am Dienstag, 16. April 2024, 16:19:10 CEST schrieb Marek Vasut:
> > > > Configure both CSI2 assigned-clock-rates the same way.
> > > > There does not seem to be any reason for keeping the
> > > > two CSI2 pixel clock set to different frequencies.
> > > > 
> > > > This also reduces first CSI2 clock from overdrive mode
> > > > frequency which is 500 MHz down below the regular mode
> > > > frequency of 400 MHz.
> > > > 
> > > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > 
> > > Apparently there is no difference when using imx415 (3840x2160) sensor.
> > 
> > Just for the records: While this change does not affect imx415 (3840x2160)
> > processing, reducing clock-frequency as well (v3) imx415 does not work.
> > So I assume that for this image size a higher than default frequency is
> > required.
> 
> For the time being I expect sensor overlays to override the default
> clock setup.

Yep, that's what I did in the end.

> Ideally the clock frequencies should be configured
> automatically at runtime by the CSI-2 RX driver.

Ideally, yes. In this case it depends on whether it is MIPI-CSI 1 in normal
or overdrive mode, if it is MIPI-CSI 2 or if both cameras a run
simultaneously. I wonder if it really worth to add that much infrastructure
for a use case which is essentially fixed setup.

Best regards,
Alexander

> > > Reviewed-by: Alexander Stein <alexander.stein at ew.tq-group.com>
> > > 
> > > > ---
> > > > Cc: Conor Dooley <conor+dt at kernel.org>
> > > > Cc: Fabio Estevam <festevam at gmail.com>
> > > > Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt at linaro.org>
> > > > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > > > Cc: Paul Elder <paul.elder at ideasonboard.com>
> > > > Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> > > > Cc: Rob Herring <robh at kernel.org>
> > > > Cc: Sascha Hauer <s.hauer at pengutronix.de>
> > > > Cc: Shawn Guo <shawnguo at kernel.org>
> > > > Cc: devicetree at vger.kernel.org
> > > > Cc: imx at lists.linux.dev
> > > > Cc: linux-arm-kernel at lists.infradead.org
> > > > ---
> > > > V2: Align both clock to 266 MHz and update commit message
> > > > ---
> > > >  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > index 1bb96e96639f2..7883f5c056f4e 100644
> > > > --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > @@ -1667,7 +1667,7 @@ mipi_csi_0: csi at 32e40000 {
> > > >  						  <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF>;
> > > >  				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_1000M>,
> > > >  							 <&clk IMX8MP_CLK_24M>;
> > > > -				assigned-clock-rates = <500000000>;
> > > > +				assigned-clock-rates = <266000000>;
> > > >  				power-domains = <&media_blk_ctrl IMX8MP_MEDIABLK_PD_MIPI_CSI2_1>;
> > > >  				status = "disabled";
> > > >  
> > > > 
> 
> 


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