* [RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request
@ 2016-05-26 3:08 ` Shawn Lin
2016-05-27 0:53 ` Jaehoon Chung
0 siblings, 1 reply; 3+ messages in thread
From: Shawn Lin @ 2016-05-26 3:08 UTC (permalink / raw)
To: Jaehoon Chung, Ulf Hansson
Cc: linux-mmc, linux-kernel, Doug Anderson, linux-rockchip, Shawn Lin
The main reason to add this check is to avoid unnecessary
mmc_request if the card is removed. Although we have already
check this in dw_mci_handle_cd for runtime usage of sd card and
dw_mci_init_slot for noremovable devices, but there is a timing
gap before it really calls dw_mci_get_cd as mmc_detect_change needs
some delay here.
Another gain here is that we could save some checkings of card status
after sd card been removed.
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
---
drivers/mmc/host/dw_mmc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index cb30e91..2940d24 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -105,6 +105,7 @@ struct idmac_desc {
static bool dw_mci_reset(struct dw_mci *host);
static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
static int dw_mci_card_busy(struct mmc_host *mmc);
+static int dw_mci_get_cd(struct mmc_host *mmc);
#if defined(CONFIG_DEBUG_FS)
static int dw_mci_req_show(struct seq_file *s, void *v)
@@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
WARN_ON(slot->mrq);
+ dw_mci_get_cd(mmc);
+
/*
* The check for card presence and queueing of the request must be
* atomic, otherwise the card could be removed in between and the
--
2.3.7
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request
2016-05-26 3:08 ` [RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request Shawn Lin
@ 2016-05-27 0:53 ` Jaehoon Chung
2016-05-27 2:26 ` Shawn Lin
0 siblings, 1 reply; 3+ messages in thread
From: Jaehoon Chung @ 2016-05-27 0:53 UTC (permalink / raw)
To: Shawn Lin, Ulf Hansson
Cc: linux-mmc, linux-kernel, Doug Anderson, linux-rockchip
Hi Shawn,
On 05/26/2016 12:08 PM, Shawn Lin wrote:
> The main reason to add this check is to avoid unnecessary
> mmc_request if the card is removed. Although we have already
> check this in dw_mci_handle_cd for runtime usage of sd card and
> dw_mci_init_slot for noremovable devices, but there is a timing
> gap before it really calls dw_mci_get_cd as mmc_detect_change needs
> some delay here.
What's unnecessary mmc_request?
>
> Another gain here is that we could save some checkings of card status
> after sd card been removed.
>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
>
> drivers/mmc/host/dw_mmc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index cb30e91..2940d24 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -105,6 +105,7 @@ struct idmac_desc {
> static bool dw_mci_reset(struct dw_mci *host);
> static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
> static int dw_mci_card_busy(struct mmc_host *mmc);
> +static int dw_mci_get_cd(struct mmc_host *mmc);
>
> #if defined(CONFIG_DEBUG_FS)
> static int dw_mci_req_show(struct seq_file *s, void *v)
> @@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>
> WARN_ON(slot->mrq);
>
> + dw_mci_get_cd(mmc);
> +
If my understanding is right, it can be replaced
if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags))
to
if (!dw_mci_get_cd(mmc))
Best Regards,
Jaehoon Chung
> /*
> * The check for card presence and queueing of the request must be
> * atomic, otherwise the card could be removed in between and the
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request
2016-05-27 0:53 ` Jaehoon Chung
@ 2016-05-27 2:26 ` Shawn Lin
0 siblings, 0 replies; 3+ messages in thread
From: Shawn Lin @ 2016-05-27 2:26 UTC (permalink / raw)
To: Jaehoon Chung, Ulf Hansson
Cc: shawn.lin, linux-mmc, linux-kernel, Doug Anderson, linux-rockchip
Hi Jaehoon,
On 2016/5/27 8:53, Jaehoon Chung wrote:
> Hi Shawn,
>
> On 05/26/2016 12:08 PM, Shawn Lin wrote:
>> The main reason to add this check is to avoid unnecessary
>> mmc_request if the card is removed. Although we have already
>> check this in dw_mci_handle_cd for runtime usage of sd card and
>> dw_mci_init_slot for noremovable devices, but there is a timing
>> gap before it really calls dw_mci_get_cd as mmc_detect_change needs
>> some delay here.
>
> What's unnecessary mmc_request?
the on-going read/write/ and the corresponding sbc like cmd13, etc.
>
>>
>> Another gain here is that we could save some checkings of card status
>> after sd card been removed.
>>
>> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
>> ---
>>
>> drivers/mmc/host/dw_mmc.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index cb30e91..2940d24 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -105,6 +105,7 @@ struct idmac_desc {
>> static bool dw_mci_reset(struct dw_mci *host);
>> static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset);
>> static int dw_mci_card_busy(struct mmc_host *mmc);
>> +static int dw_mci_get_cd(struct mmc_host *mmc);
>>
>> #if defined(CONFIG_DEBUG_FS)
>> static int dw_mci_req_show(struct seq_file *s, void *v)
>> @@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>>
>> WARN_ON(slot->mrq);
>>
>> + dw_mci_get_cd(mmc);
>> +
>
> If my understanding is right, it can be replaced
>
> if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags))
>
> to
>
> if (!dw_mci_get_cd(mmc))
yeah~ It looks better.
>
>
> Best Regards,
> Jaehoon Chung
>
>
>
>> /*
>> * The check for card presence and queueing of the request must be
>> * atomic, otherwise the card could be removed in between and the
>>
>
>
>
>
--
Best Regards
Shawn Lin
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-26 3:08 ` [RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request Shawn Lin
2016-05-27 0:53 ` Jaehoon Chung
2016-05-27 2:26 ` Shawn Lin
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