On 20 March 2013 06:41, <Chang-Ming.Huang@xxxxxxxxxxxxx> wrote:
> From: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
>
> In order to check whether the card has been removed, the function
> mmc_send_status() will send command CMD13 to card and ask the card
> to send its status register to sdhc driver, which will generate
> many interrupts repeatedly and make the system performance bad.
> From the performance test on Freescale's board (such as Iozone for SD),
> the performance will degrade about 4~6%.
>
> There is one another way to get this information,
> which is to read the register PRSSTAT and check the bit CDPL or CINS.
> If the card is present, these two bit will set to one.
> Therefore, add callback function get_cd() to check whether
> the card has been inserted/removed when the driver supports this feature.
> If the card is present, 0 will return, if the card is absent, 1 will return.
> If the controller will not support this feature, -ENOSYS will return.
>
> Signed-off-by: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx>
> Reviewed-by: Johan Rudholm <johan.rudholm@xxxxxxxxxxxxxx>
> Reviewed-by: Anton Vorontsov <cbouatmailru@xxxxxxxxx>
> CC: Chris Ball <cjb@xxxxxxxxxx>
> ---
> changes for v2:
> - when controller don't support get_cd, return -ENOSYS
> - add the CC
> changes for v3:
> - enalbe the controller clock in platform, instead of core
> changes for v4:
> - move the detect code to core.c according to the new structure
> changes for v5:
> - reviewed by Anton and Johan, add the reviewed-by.
> changes for v6:
> - add more comment.
>
> drivers/mmc/core/core.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 08a3cf2..e225deb 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2280,7 +2280,7 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
>
> int _mmc_detect_card_removed(struct mmc_host *host)
> {
> - int ret;
> + int ret = -ENOSYS;
>
> if ((host->caps & MMC_CAP_NONREMOVABLE) || !host->bus_ops->alive)
> return 0;
> @@ -2288,7 +2288,19 @@ int _mmc_detect_card_removed(struct mmc_host *host)
> if (!host->card || mmc_card_removed(host->card))
> return 1;
>
> - ret = host->bus_ops->alive(host);
> + /* First, try host-controller's card detect callback */
> + if (host->ops->get_cd) {
> + ret = host->ops->get_cd(host);
> + /*
> + * The return value from get_cd: 1 for present, 0 for absent,
> + * we need to convert it to: 1 for absent, 0 for present.
> + */
> + if (ret >= 0)
> + ret = !ret;
> + }
> + /* If failed, back to the bus_ops alive() callback */
> + if (ret < 0)
> + ret = host->bus_ops->alive(host);
> if (ret) {
> mmc_card_set_removed(host->card);
> pr_debug("%s: card remove detected\n", mmc_hostname(host));
I guess this already has been fixed by Kevin's patch below.
http://article.gmane.org/gmane.linux.kernel.mmc/19481
> --
> 1.7.9.5
>
>
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Kind regards
Ulf Hansson
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