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authorDouglas Anderson <dianders@chromium.org>2017-10-12 13:11:15 -0700
committerUlf Hansson <ulf.hansson@linaro.org>2017-10-30 12:14:52 +0100
commit4c2357f57dd5a3ecb4ce09f6a6cb394a1a8873b2 (patch)
treee49c6dce1687512566137ec62d394e358aee2a77 /drivers/mmc
parent0363b12d3311eaf1355d4b9272a51dd852ea2fc1 (diff)
mmc: dw_mmc: Fix the CTO timeout calculation
In the commit 03de19212ea3 ("mmc: dw_mmc: introduce timer for broken command transfer over scheme") we tried to calculate the expected hardware command timeout value. Unfortunately that calculation isn't quite correct in all cases. 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: It's not expected that this will actually fix anything important since the 10 ms margin added by the function will pretty much dwarf any calculations. The card clock should be 100 kHz at minimum and: 1000 ms/s * (255 * 2) / 100000 Hz. Gives us 5.1 ms. ...so really the point of this patch is just to make the code more "correct" in case anyone ever tries to remove the 10 ms buffer. Fixes: 03de19212ea3 ("mmc: dw_mmc: introduce timer for broken command transfer over scheme") Tested-by: Emil Renner Berthing <kernel@esmil.dk> Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/dw_mmc.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index f5b2bb4b4d98..16516c528a88 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -401,10 +401,14 @@ static u32 dw_mci_prep_stop_abort(struct dw_mci *host, struct mmc_command *cmd)
static inline void dw_mci_set_cto(struct dw_mci *host)
{
unsigned int cto_clks;
+ unsigned int cto_div;
unsigned int cto_ms;
cto_clks = mci_readl(host, TMOUT) & 0xff;
- cto_ms = DIV_ROUND_UP(cto_clks, host->bus_hz / 1000);
+ cto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
+ if (cto_div == 0)
+ cto_div = 1;
+ cto_ms = DIV_ROUND_UP(MSEC_PER_SEC * cto_clks * cto_div, host->bus_hz);
/* add a bit spare time */
cto_ms += 10;