Hello Jaehoon, On 2016년 06월 17일 10:30, Jaehoon Chung wrote: > Hi Seung-Woo, > > On 06/10/2016 10:29 AM, Seung-Woo Kim wrote: >> Hi Jaehoon, >> >> On 2016년 06월 09일 21:38, Jaehoon Chung wrote: >>> Hi Seung-Woo, >>> >>> On 06/08/2016 01:07 PM, Seung-Woo Kim wrote: >>>> This patch removes following UBSAN warnings in dw_mci_setup_bus(). >>>> The warnings are caused because of shift with more than 31 on 32 >>>> bit variable, so this patch fixes to shift only for less than 32. >>>> <snip.> >>>> >>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >>>> index 2cc6123..dff045e 100644 >>>> --- a/drivers/mmc/host/dw_mmc.c >>>> +++ b/drivers/mmc/host/dw_mmc.c >>>> @@ -1099,7 +1099,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) >>>> >>>> div = (host->bus_hz != clock) ? DIV_ROUND_UP(div, 2) : 0; >>>> >>>> - if ((clock << div) != slot->__clk_old || force_clkinit) >>>> + if (((div < 32) ? (clock << div) : 0) != slot->__clk_old || >>> >>> Well, we don't expect that clock is 0. >>> if clock is 0, it should be passed to " if (!clock)".. >>> >>> During initializing card, clock is 400KHz or less..I understood what you want to fix. >>> But I taught this is not correct. >> >> It seems slot->__clk_old is not really clock but a kind of value to >> store both clock and div in one variable. And at least, my compiler >> calculates right shift with more than 32 as 0. I am not sure there is >> other proper value for the case. >> >> By the way, in my test environment, clock is calculated as like >> following steps: >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 400000Hz, >> actual 400000HZ div = 250) >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 200000000Hz, >> actual 200000000HZ div = 0) >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 52000000Hz, >> actual 50000000HZ div = 2) >> mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 52000000Hz, >> actual 50000000HZ div = 4) >> mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 200000000Hz, >> actual 200000000HZ div = 1) >> >> and only the first case is reported as the warning. If you let me know >> any proper value, then I will fix with the value. > > I think that "clock << div" and__old_clock are used for checking whether clock is changed. > So it doesn't need to rotate with div. > > Could you check the below codes? > > if ((clock != slot->clk_old) || force_clkinit) > ... > > slot->__clk_old = clock; >From the comment about alignment of slot->__clk_old, it says that "keep the clock with reflecting clock dividor". So to me, it is better also adding slot->__dlv with your suggestion. I will send patch like it, soon. Regards, - Seung-Woo Kim > > Best Regards, > Jaehoon Chung > >> >> Thanks, >> - Seung-Woo Kim >> >> >>> >>> >>>> + force_clkinit) >>>> dev_info(&slot->mmc->class_dev, >>>> "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ div = %d)\n", >>>> slot->id, host->bus_hz, clock, >>>> @@ -1129,7 +1130,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) >>>> mci_send_cmd(slot, sdmmc_cmd_bits, 0); >>>> >>>> /* keep the clock with reflecting clock dividor */ >>>> - slot->__clk_old = clock << div; >>>> + slot->__clk_old = (div < 32) ? (clock << div) : 0; <snip.> -- Seung-Woo Kim Samsung Software R&D Center -- -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
