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Date: Mon, 4 Dec 2017 23:25:27 +0000 From: André Przywara <andre.przywara@....com> To: wens@...e.org, Maxime Ripard <maxime.ripard@...e-electrons.com>, Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...eaurora.org> Cc: linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com Subject: Re: [linux-sunxi] [PATCH 0/2] clk: sunxi-ng: sun50i: a64: Add 2x fixed post-divider to MMC module clocks 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 <andre.przywara@....com> Given the impact I wonder if this is a candidate for stable as well. > 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? 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(-) >
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