From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 2/5] drivers: mmc: sunxi: limit A64 MMC2 to 8K DMA buffer Date: Tue, 10 Jan 2017 15:06:00 +0100 Message-ID: <20170110140600.wr7qyz3d2ri536mt@lukather> References: <1483398226-29321-1-git-send-email-andre.przywara@arm.com> <1483398226-29321-3-git-send-email-andre.przywara@arm.com> <20170104140750.7qs4pvggwjdj5cma@rob-hp-laptop> <20170105175746.fq6crpc3krz7tzxi@lukather> <87b26848-4f86-f2d2-3f82-db0937c572e2@arm.com> Reply-To: maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2qmu4zrtesiijmpm" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: <87b26848-4f86-f2d2-3f82-db0937c572e2-5wv7dgnIgG8@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: =?iso-8859-1?Q?Andr=E9?= Przywara Cc: Rob Herring , Ulf Hansson , Chen-Yu Tsai , Hans De Goede , Icenowy Zheng , Mark Rutland , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-mmc@vger.kernel.org --2qmu4zrtesiijmpm Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 05, 2017 at 11:33:28PM +0000, Andr=C3=A9 Przywara wrote: > On 05/01/17 17:57, Maxime Ripard wrote: > > Hi Rob, > >=20 > > 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 > >>> > >>> 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 tha= t > >>> particular device. This will also help to enable the high-speed trans= fer > >>> modes of that controller later. > >>> > >>> Signed-off-by: Maxime Ripard > >>> Signed-off-by: Andre Przywara > >>> --- > >>> Documentation/devicetree/bindings/mmc/sunxi-mmc.txt | 1 + > >>> drivers/mmc/host/sunxi-mmc.c | 7 +++++++ > >>> 2 files changed, 8 insertions(+) > >> > >> Acked-by: Rob Herring > >=20 > > 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. > >=20 > > 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? >=20 > 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? That would be my understanding too, at least, it works in a decent way without fiddling with those parameters. Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com --=20 You received this message because you are subscribed to the Google Groups "= linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to linux-sunxi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout. --2qmu4zrtesiijmpm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJYdOpEAAoJEBx+YmzsjxAgp+EP/3hVaW9DMYH6QpzxZR2sH1Xv usHFZMrX2IlFUk9Dp5GdMZ1B1Lf0u90CW0kh2pnY3FPEKjsGFiFXjHISQB1NKBc8 Wk9agm+c0FvfKZQ7IQNkx5T6DWRXoibWxJUbjW8+wdG4isR7vwmJkLCSsNzZG8H8 RtjE1tTZjeYiDDXl0osu9M1ozqc26Yoyu3yhTVApzkhG9Z2UANjwItTmcb/lv+Sb 8mFPx5ra9KnWTmL9tJnLVTIC8e+zThcCJtH8IUZJQNqshTJ1WBilnJIuK3HzD2wO Ew0vkcNjx8h1uxLwNOI4hKi/zch5dwDNuHf+OUv3vMR1nB+Rs2x33rq0rwh3HtNw 001AYRG1Q8Dalf2z0PrWN+bLf+t/LxheXRknwQcqOFZ0KQMNZj0DEO8PXJZe8MMl vBM6Bfhc83slszRzDcFMKBLl9ryN4nop7SsvgKR7wsROWCXKvXw7jMXOo/2EOTrI rmqDbL7OiToDyofil4yGuGYxMd3/mDpWcsAnJwMxKzpVd2NiiGQ1aJQPgDDxyzBn YCO//ZH+RPtgYPJGWfzLeaRNPyHpg4h7cX7AJMnlmf2pbi/it0sD1O2vRNGEsCA2 7cliUT6RFaY5HcSRFFSb3aZq67K1WfaBMYWlx98jCAP7MDdQMyJpbIVNNRaikT4F 4B6igcgJAH43Y3iNdyRH =tXUP -----END PGP SIGNATURE----- --2qmu4zrtesiijmpm--