Re: [PATCH] ARM: dts: i.MX25: define SSI FIFO depth

[Martin Kaiser]

Hi Lothar,

Thus wrote Lothar Waßmann (LW@xxxxxxxxxxxxxxxxxxx):

> On Thu, 8 Mar 2018 16:38:32 +0100 Martin Kaiser wrote:
> > Hi Lothar,

> > Thus wrote Lothar Waßmann (LW@xxxxxxxxxxxxxxxxxxx):

> > > > diff --git a/arch/arm/boot/dts/imx25.dtsi b/arch/arm/boot/dts/imx25.dtsi
> > > > index 9725705..cf70df2 100644
> > > > --- a/arch/arm/boot/dts/imx25.dtsi
> > > > +++ b/arch/arm/boot/dts/imx25.dtsi
> > > > @@ -269,6 +269,7 @@
> > > >  				dmas = <&sdma 24 1 0>,
> > > >  				       <&sdma 25 1 0>;
> > > >  				dma-names = "rx", "tx";
> > > > +				fsl,fifo-depth = <15>;
> > > >  				status = "disabled";
> > > >  			};

> > > > @@ -329,6 +330,7 @@
> > > >  				dmas = <&sdma 28 1 0>,
> > > >  				       <&sdma 29 1 0>;
> > > >  				dma-names = "rx", "tx";
> > > > +				fsl,fifo-depth = <15>;
> > > >  				status = "disabled";
> > > >  			};

> > > You are changing the global .dtsi file. Did you test this change with
> > > all devices that are affected by it?

> > I changed the hardware description of the imx25 SSI to match the
> > reference manual.

> > I did test this change on an imx25 board with audio playback. This uses
> > the SSI description I modified. I verified that the driver is actually
> > taking the modified setting into account and that this causes no
> > problems.

> > As of today, this setting is used by the fsl_ssi driver to set the fifo
> > water level for dma requests.

> > Of course, I don't have access to the enitre range of supported imx25
> > boards and I don't think this is required for submitting patches.

> > Do you have any indication why this patch should not be merged?

> Usually patches should not willy-nilly change the behaviour of existing
> configurations unless they fix any real life bugs.

We both made our points, let the maintainer decide what to do with the
patch.

Thanks & Best regards,

   Martin