| Message ID | 20171012201118.23570-5-dianders@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017/10/13 4:11, Douglas Anderson wrote: > 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> > --- > > Changes in v2: > - Fix the DTO timeout calculation new for v2 > > drivers/mmc/host/dw_mmc.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index 50148991f30e..6bc87b1385a9 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -1936,10 +1936,16 @@ 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; > + unsigned long irqflags; > > 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; > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 50148991f30e..6bc87b1385a9 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1936,10 +1936,16 @@ 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; + unsigned long irqflags; 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;
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> --- Changes in v2: - Fix the DTO timeout calculation new for v2 drivers/mmc/host/dw_mmc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)