From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Date: Tue, 19 Jul 2016 16:51:11 +0900 Subject: [U-Boot] [PATCH] mmc: dw_mmc: reduce timeout detection cycle In-Reply-To: <578DD95C.9050806@rock-chips.com> References: <1468892302-3956-1-git-send-email-xzy.xu@rock-chips.com> <578D8A57.7000404@samsung.com> <578D9160.1030005@rock-chips.com> <578DAB0A.4060606@samsung.com> <578DD95C.9050806@rock-chips.com> Message-ID: <578DDBEF.60307@samsung.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 07/19/2016 04:40 PM, Ziyuan Xu wrote: > Hi Jaehoon, > > On 2016?07?19? 12:22, Jaehoon Chung wrote: >> Hi Ziyuan, >> >> On 07/19/2016 11:33 AM, Ziyuan Xu wrote: >>> Hi Jaehoon, >>> >>> On 2016?07?19? 10:03, Jaehoon Chung wrote: >>>> Hi Ziyuan, >>>> >>>> On 07/19/2016 10:38 AM, Ziyuan Xu wrote: >>>>> It's no need to speed 10 seconds to wait the mmc device out from busy >>>>> status. 500 milliseconds enough. >>>> I agreed that 10 seconds is too big.. >>>> Could you explain more how you get 500ms and feel enough? >>> Ordinarily, there are 3 types of scenarios that the mmc device was busy: >>> 1. The mmc interface didn't initialize (eg. gpio iomux) >>> The device will be busy status until gpio iomux. >>> >>> 2. The last command with data transfer. >>> The maximum value of data timeout is 0xffffff cyles(see dwi databook Timeout Register), and the clock is up to 52MHZ under high speed mode. >>> timeout = 0xffffff * 1/52M = 0.32s >>> >>> 3. voltage switch >>> U-BOOT doesn't support voltage switch. >>> >>> In summary, I think 500 milliseconds is enough. What do you think? >> I think it's not important thing. >> >> This is for checking whether card is busy or not before sending command. >> I think it's not relevant to Timeout register. Just ensure that card is not busy before sending command. >> And there is no effect for I/O performance, isn't? > Yup, I agree with you. For scenarios 2, I mean that if the last command with data transfer, we will hit data_busy assertion probably. If the mmc device remains in a busy state more than 500ms, I think it may also be busy state after 10s. >> >> But 50ms is not bad. :) It's personal preference. > BTW, the timeout value is 500ms in kernel. Yep, it looks good to me. :) I have tested your patch with Exynos SoCs. Reviewed-by: Jaehoon Chung Tested-by: Jaehoon Chung Best Regards, Jaehoon Chung >> >> Best Regards, >> Jaehoon Chung >> >>>> Best Regards, >>>> Jaehoon Chung >>>> >>>>> Signed-off-by: Ziyuan Xu >>>>> --- >>>>> >>>>> drivers/mmc/dw_mmc.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c >>>>> index 2cf7bae..790a166 100644 >>>>> --- a/drivers/mmc/dw_mmc.c >>>>> +++ b/drivers/mmc/dw_mmc.c >>>>> @@ -195,7 +195,7 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, >>>>> ALLOC_CACHE_ALIGN_BUFFER(struct dwmci_idmac, cur_idmac, >>>>> data ? DIV_ROUND_UP(data->blocks, 8) : 0); >>>>> int ret = 0, flags = 0, i; >>>>> - unsigned int timeout = 100000; >>>>> + unsigned int timeout = 500; >>>>> u32 retry = 100000; >>>>> u32 mask, ctrl; >>>>> ulong start = get_timer(0); >>>>> >>>> >>>> >>> >>> >>> >>> >> >> >> > > > > >