From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ziyuan Xu Date: Tue, 19 Jul 2016 15:40:12 +0800 Subject: [U-Boot] [PATCH] mmc: dw_mmc: reduce timeout detection cycle In-Reply-To: <578DAB0A.4060606@samsung.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> Message-ID: <578DD95C.9050806@rock-chips.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 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. > > 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); >>>> >>> >>> >> >> >> >> > > >