On Mon, 15 Feb 2021 at 01:33, Luca Porzio <porzio@xxxxxxxxx> wrote:
>
> cmdq_en attribute in sysfs now can now be written.
> When 0 is written:
> CMDQ is disabled and kept disabled across device reboots.
> When 1 is written:
> CMDQ mode is instantly reneabled (if supported).
>
> Signed-off-by: Luca Porzio <lporzio@xxxxxxxxxx>
> Signed-off-by: Zhan Liu <zliua@xxxxxxxxxx>
> ---
> drivers/mmc/core/mmc.c | 152 ++++++++++++++++++++++++++++++---------
> include/linux/mmc/card.h | 1 +
> 2 files changed, 118 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
[...]
> +static ssize_t cmdq_en_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct mmc_card *card = mmc_dev_to_card(dev);
> + struct mmc_host *host = card->host;
> + unsigned long enable;
> + int err;
> +
> + if (!card || kstrtoul(buf, 0, &enable))
> + return -EINVAL;
> + if (!card->ext_csd.cmdq_support)
> + return -EOPNOTSUPP;
> +
> + enable = !!enable;
> + if (enable == card->ext_csd.cmdq_en)
> + return count;
> +
> + mmc_get_card(card, NULL);
This means adding a new path for when the host needs to get locked
(claimed), which is the opposite direction of what we have been
working on for SD/eMMC during the last couple of years.
Please have a look at mmc_blk_issue_drv_op(), where you can find how
these kinds of requests are being funneled through the mmc block
device layer instead. This is the preferred option.
That said, I am actually wondering if we perhaps could manage the
enable/disable of CQE "automagically" for FFU, along the lines of what
we do for RPMB already. In fact, maybe the best/easiest approach is to
*always* disable CQE when there is a request being received through
the mmc ioctl interface. Of course, then if we disabled CQE we should
also re-enable it when the ioctl request has been completed.
What do you think?
> + card->force_disable_cmdq = !enable;
> + err = mmc_cmdq_setup(host, card);
> + mmc_put_card(card, NULL);
> +
> + if (err)
> + return err;
> + else
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(cmdq_en);
> +
>
[...]
Kind regards
Uffe
