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@xxxxxxxxxxxxxx>
> ---
>
> 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
>
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