From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752334AbdLEDFN convert rfc822-to-8bit (ORCPT ); Mon, 4 Dec 2017 22:05:13 -0500 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:37400 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750995AbdLEDFK (ORCPT ); Mon, 4 Dec 2017 22:05:10 -0500 X-Google-Smtp-Source: AGs4zMa7S/RGy/GXbKHqSdLg1cAvQPm5JhqrYdLWZboHZ3/yWuFdI2CipHJnxOUIalKWhgcA+psGRp2hfn7NX3RaeCI= MIME-Version: 1.0 In-Reply-To: <25d0eff3-a0d9-fb49-8287-e65a4a102db7@arm.com> References: <20171204051912.7485-1-wens@csie.org> <25d0eff3-a0d9-fb49-8287-e65a4a102db7@arm.com> From: Chen-Yu Tsai Date: Tue, 5 Dec 2017 11:04:45 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [linux-sunxi] [PATCH 0/2] clk: sunxi-ng: sun50i: a64: Add 2x fixed post-divider to MMC module clocks To: =?UTF-8?Q?Andr=C3=A9_Przywara?= Cc: Chen-Yu Tsai , Maxime Ripard , Michael Turquette , Stephen Boyd , linux-arm-kernel , linux-clk , linux-kernel , linux-sunxi Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 5, 2017 at 7:25 AM, André Przywara wrote: > On 04/12/17 05:19, Chen-Yu Tsai wrote: >> Hi, >> >> This is a small fix to get MMC performance up to proper speeds on the > > Maybe a small fix for a skilled developer, but a giant leap for all > users ;-) > MMC performance goes from: (4.15-rc1) > > SD: Timing buffered disk reads: 36 MB in 3.17 seconds = 11.35 MB/sec > eMMC: Timing buffered disk reads: 66 MB in 3.03 seconds = 21.81 MB/sec > > to: (4.15-rc2 plus those two patches) > > SD: Timing buffered disk reads: 68 MB in 3.01 seconds = 22.61 MB/sec > eMMC: Timing buffered disk reads: 132 MB in 3.01 seconds = 43.80 MB/sec > > So yes, factor of two ... > > Tested-by: Andre Przywara > > Given the impact I wonder if this is a candidate for stable as well. It could. But then again, nothing was broken. And it depends on the first patch. I'm not sure stable would like that. > >> A64. According to the BSP kernel, the MMC module clocks have a /2 fixed >> post-divider between the clock output and the MMC module, like what >> we've seen with the "new MMC timing mode" on the A83T, but the A64 does >> not have the mode switch. >> >> Sub-par performance was observed on the Banana Pi M64 eMMC. It only >> reached half the read throughput of other Banana Pi boards, using a >> standard sequential readout with a large block size. After these >> patches, the performance is up to spec. >> >> The A64 can also do DDR transfer modes, but the clock delay config >> registers in the MMC module are different from what we've seen so >> far. > > But the BSP doesn't set those as well, does it? I mean to remember that > they were all zero, expect for HS200/HS400? What I meant was we should make it clear in the mmc driver that this is another new configuration mechanism that is different from the previous ones. ChenYu > > Thanks! > Andre. > >> One can just force enable DDR modes without tuning the delays, >> and it does work. Proper support for this is left for another time. >> >> >> ChenYu >> >> Chen-Yu Tsai (2): >> clk: sunxi-ng: Support fixed post-dividers on MP style clocks >> clk: sunxi-ng: sun50i: a64: Add 2x fixed post-divider to MMC module >> clocks >> >> drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 57 +++++++++++++++++++++++------------ >> drivers/clk/sunxi-ng/ccu_mp.c | 20 ++++++++++-- >> drivers/clk/sunxi-ng/ccu_mp.h | 24 +++++++++++++++ >> 3 files changed, 79 insertions(+), 22 deletions(-) >> >