Am Freitag, 8. März 2019, 14:10:45 CET schrieb Christoph Müllner: > > > On 08.03.2019, at 13:46, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > > > > On 7/03/19 10:43 AM, Christoph Muellner wrote: > >> This patch documents the new property disable-cqe-dcmd > >> for the Arasan eMMC 5.1 driver. > >> > >> Signed-off-by: Christoph Muellner <christoph.muellner@xxxxxxxxxxxxxxxxxxxxx> > >> Signed-off-by: Philipp Tomsich <philipp.tomsich@xxxxxxxxxxxxxxxxxxxxx> > >> --- > >> Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > >> index 1edbb049cccb..ec699bf98b7c 100644 > >> --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > >> +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > >> @@ -44,6 +44,10 @@ Optional Properties: > >> properly. Test mode can be used to force the controller to function. > >> - xlnx,int-clock-stable-broken: when present, the controller always reports > >> that the internal clock is stable even when it is not. > >> + - disable-cqe-dcmd: The eMMC 5.1 standard specifies direct commands (DCMDs) > >> + as part of the command queue engine (CQE). On controllers with a CQHCI, > >> + such as the Arasan eMMC 5.1 host controller, the driver has to enable DCMDs. > >> + This is done unless disable-cqe-dcmd is specified. This needs a rewording please. See below for hw-description vs. driver, so the description should be centered around why this is a property of the hw [like faulty controller implementation or whatever] > > If "supports-cqe" is in mmc.txt, should "disable-cqe-dcmd" be there also? > > The file mmc.txt says on top: > "These properties are common to multiple MMC host controllers". > As my patchset introduces "disable-cqe-dcmd" just for sdhci-of-arasan, > I would say it should not go into that file. > > Also I wonder why "supports-cqe" is in mmc.txt, because > only sdhci-tegra.c is evaluating that property. > So I would expect it to be documented in > Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt > > However, I see that "disable-cqe-dcmd" could go into other drivers as well. > But is this enough to document it in mmc.txt? Devicetree is always about describing the hardware capabilites and never about the actual nitty-gritty of driver implementation, aka it is not meant as a space for hardware-independent config-settings or such. As for only tegra evaluating this, is probably because it is still so new, like january 2019 and Rob explicitly suggested it becoming common [0], which suggests that the disable-cqe-dcmds should probably also be common. Heiko [0] https://lore.kernel.org/patchwork/patch/1031163/
