Re: [PATCH v4] mmc: dw_mmc: Fix the DTO/CTO timeout overflow calculation for 32-bit systems

[Jisheng Zhang <Jisheng.Zhang@synaptics.com>]

On Wed, 28 Feb 2018 14:53:18 +0300 Evgeniy Didin wrote:

> In commit 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation") and
> commit 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation") 
> have been made changes which cause multiply overflow for 32-bit systems.
> The broken timeout calculations leads to unexpected ETIMEDOUT errors and 
> causes stacktrace splat (such as below) during normal data exchange 
> with SD-card.
> 
> | Running :  4M-check-reassembly-tcp-cmykw2-rotatew2.out -v0 -w1
> | -  Info: Finished target initialization.
> | mmcblk0: error -110 transferring data, sector 320544, nr 2048, cmd response
> |  0x900, card status 0x0
> 
> DIV_ROUND_UP_ULL helps to escape usage of __udivdi3() from libgcc and so
> code gets compiled on all 32-bit platforms as opposed to usage
> of DIV_ROUND_UP when we may only compile stuff on a very few arches.
> 
> Lets cast this multiply to u64 type which prevents overflow.

Reviewed-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>

> 
> Tested-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
> Reported-by: Vineet Gupta <Vineet.Gupta1@synopsys.com> # ARC STAR 9001306872 HSDK, sdio: board crashes when copying big files
> Fixes: 9d9491a7da2a ("mmc: dw_mmc: Fix the DTO timeout calculation")
> Fixes: 4c2357f57dd5 ("mmc: dw_mmc: Fix the CTO timeout calculation")
> 
> Signed-off-by: Evgeniy Didin <Evgeniy.Didin@synopsys.com>
> 
> CC: Alexey Brodkin <abrodkin@synopsys.com>
> CC: Eugeniy Paltsev <paltsev@synopsys.com>
> CC: Douglas Anderson <dianders@chromium.org>
> CC: Ulf Hansson <ulf.hansson@linaro.org>
> CC: Andy Shevchenko <andy.shevchenko@gmail.com>
> CC: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> CC: Shawn Lin <shawn.lin@rock-chips.com>
> CC: Vineet Gupta <Vineet.Gupta1@synopsys.com>
> CC: linux-kernel@vger.kernel.org
> CC: linux-snps-arc@lists.infradead.org
> Cc: <stable@vger.kernel.org> 
> ---
> Changes since v3:
> -Switch DIV_ROUND_UP macro to DIV_ROUND_UP_ULL
> -Make one patch from two patches
> -Modify commit message
> 
> Changes sinve v2:
> -add fix for cto_ms
> 
> Changes since v1:
> -uint64_t switched to u64
> 
>  drivers/mmc/host/dw_mmc.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 0aa39975f33b..cba534d4c81b 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -409,7 +409,9 @@ static inline void dw_mci_set_cto(struct dw_mci *host)
>  	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);
> +
> +	cto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * cto_clks * cto_div,
> +				  host->bus_hz);
>  
>  	/* add a bit spare time */
>  	cto_ms += 10;
> @@ -1944,8 +1946,9 @@ static void dw_mci_set_drto(struct dw_mci *host)
>  	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);
> +
> +	drto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * drto_clks * drto_div,
> +				   host->bus_hz);
>  
>  	/* add a bit spare time */
>  	drto_ms += 10;