diff options
| author | Douglas Anderson <dianders@chromium.org> | 2017-10-12 13:11:17 -0700 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2017-11-01 15:13:45 +0100 |
| commit | 9d9491a7da2a4ce9fed32bd8611992ea3471523a (patch) | |
| tree | bb7a26b38e54f61396eba6f3bfcf449f0f2f5033 /drivers | |
| parent | 8892b705f58e105b0b4ce3402afa1d1b803fb207 (diff) | |
| download | linux-9d9491a7da2a4ce9fed32bd8611992ea3471523a.tar.bz2 | |
mmc: dw_mmc: Fix the DTO timeout calculation
Just like the CTO timeout calculation introduced recently, the DTO
timeout calculation was incorrect. It used "bus_hz" but, as far as I
can tell, it's supposed to use the card clock. Let's account for the
div value, which is documented as 2x the value stored in the register,
or 1 if the register is 0.
NOTE: This was likely not terribly important until commit 16a34574c6ca
("mmc: dw_mmc: remove the quirks flags") landed because "DIV" is
documented on Rockchip SoCs (the ones that used to define the quirk)
to always be 0 or 1. ...and, in fact, it's documented to only be 1
with EMMC in 8-bit DDR52 mode. Thus before the quirk was applied to
everyone it was mostly OK to ignore the DIV value.
I haven't personally observed any problems that are fixed by this
patch but I also haven't tested this anywhere with a DIV other an 0.
AKA: this problem was found simply by code inspection and I have no
failing test cases that are fixed by it. Presumably this could fix
real bugs for someone out there, though.
Fixes: 16a34574c6ca ("mmc: dw_mmc: remove the quirks flags")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mmc/host/dw_mmc.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 50148991f30e..4f2806720c5c 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1936,10 +1936,15 @@ static int dw_mci_data_complete(struct dw_mci *host, struct mmc_data *data) static void dw_mci_set_drto(struct dw_mci *host) { unsigned int drto_clks; + unsigned int drto_div; unsigned int drto_ms; drto_clks = mci_readl(host, TMOUT) >> 8; - drto_ms = DIV_ROUND_UP(drto_clks, host->bus_hz / 1000); + drto_div = (mci_readl(host, CLKDIV) & 0xff) * 2; + if (drto_div == 0) + drto_div = 1; + drto_ms = DIV_ROUND_UP(MSEC_PER_SEC * drto_clks * drto_div, + host->bus_hz); /* add a bit spare time */ drto_ms += 10; |