On 05/01/17 17:57, Maxime Ripard wrote: > Hi Rob, > > On Wed, Jan 04, 2017 at 08:07:50AM -0600, Rob Herring wrote: >> On Mon, Jan 02, 2017 at 11:03:43PM +0000, Andre Przywara wrote: >>> From: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> >>> >>> Unlike the A64 user manual reports, the third MMC controller on the >>> A64 (and the only one capable of 8-bit HS400 eMMC transfers) has a >>> DMA buffer size limit of 8KB (much like the very old Allwinner SoCs). >>> This does not affect the other two controllers, so introduce a new >>> DT compatible string to let the driver use different settings for that >>> particular device. This will also help to enable the high-speed transfer >>> modes of that controller later. >>> >>> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> >>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> >>> --- >>> Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 + >>> drivers/mmc/host/sunxi-mmc.c | 7 +++++++ >>> 2 files changed, 8 insertions(+) >> >> Acked-by: Rob Herring <robh@xxxxxxxxxx> > > Some kind of a digression on this: we have three MMC controllers on > this SoC. Like this patch shows, the third one is clearly different, > and supports both more modes, a wider bus, and specific quirks. We > need a new compatible for this one, everything's perfect. > > However, the other two are mostly the same, but seems to need > different tuning parameters to get more performances out of the > controller (but this is unclear yet). How do we usually deal with > that? I guess you wanted to hear Rob's opinion ;-), but "get more performance" sounds like we add one (or more) properties to tune those values. If I get this right, it works with default values, but is sub-optimal? Cheers, Andre. -- 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
