Hi Jaehoon,
On 2016年07月19日 12:22, Jaehoon Chung wrote:
Hi Ziyuan,
On 07/19/2016 11:33 AM, Ziyuan Xu wrote:
Hi Jaehoon,
On 2016年07月19日 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 <xzy...@rock-chips.com>
---
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);
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