On Thu, 9 Aug 2018 08:23:16 -0400 Peter Geis <pgwipeout@xxxxxxxxx> wrote: > On 08/09/2018 08:02 AM, Aapo Vienamo wrote: > > On Thu, 9 Aug 2018 13:49:22 +0200 > > Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > > > >> On Tue, Aug 07, 2018 at 05:00:01PM +0300, Aapo Vienamo wrote: > >>> Add the HS400 DQS trim value for Tegra186 SDMMC4. > >>> > >>> Signed-off-by: Aapo Vienamo <avienamo@xxxxxxxxxx> > >>> --- > >>> arch/arm64/boot/dts/nvidia/tegra186.dtsi | 1 + > >>> 1 file changed, 1 insertion(+) > >>> > >>> diff --git a/arch/arm64/boot/dts/nvidia/tegra186.dtsi b/arch/arm64/boot/dts/nvidia/tegra186.dtsi > >>> index 6e9ef26..9e07bc6 100644 > >>> --- a/arch/arm64/boot/dts/nvidia/tegra186.dtsi > >>> +++ b/arch/arm64/boot/dts/nvidia/tegra186.dtsi > >>> @@ -313,6 +313,7 @@ > >>> nvidia,pad-autocal-pull-down-offset-1v8-timeout = <0x0a>; > >>> nvidia,default-tap = <0x5>; > >>> nvidia,default-trim = <0x9>; > >>> + nvidia,dqs-trim = <63>; > >>> status = "disabled"; > >>> }; > >>> > >> > >> Isn't this technically dependent on the board layout and as such would > >> belong in the board DTS file? Or does this value work on all existing > >> Tegra186 platforms? > > > > This value is specified as part of the controller initialization > > sequence in the TRM. I've understood that this (and other tap and trim) > > value(s) are used for compensating the propagation delay differences > > that are caused by the internal SoC layout. > > > > -Aapo > > -- > > The Tegra2 and Tegra3 TRMs also specify recommended DQS values, and I am > working on at least one device that differs in the platform data from > the default value. > I see that you mentioned this is for the newer devices that support > HS200/HS400 modes, but does it enable setting DQS on older devices? I can't find any mention of _SDMMC_ DQS trimmer on Tegra2, Tegra3 or Tegra124 TRMs. As far as I can tell, programming the DQS trimmer value is only required by HS400 signaling on Tegra210 and Tegra186. -Aapo -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
