On Sat, 26 Jun 2021 at 20:58, Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hi Adrian, Ulf, everyone,
>
> > With the code above, if the host controller knows the card has been
> > removed, it can return -ENOMEDIUM from ->execute_tuning() to suppress
> > the message.
>
> On second thought, I like the idea with -ENOMEDIUM. Because tuning can
> still fail for reasons other than a removed card and we want to see an
> error message then.
>
> So, I checked when/how to return -ENOMEDIUM for the SDHI driver but this
> lead me to more questions. The few driver which return this error code
> all follow a similar pattern:
>
> xxx_request()
> {
> if (host->get_cd == 1)
> submit_mrq
> else
> cmd->error = -ENOMEDIUM
> mmc_request_done()
> }
>
> So, my first question would be if we can't apply this pattern in the
> core before calling the .request callback? A lot of drivers are not
> implementing this pattern although it seems useful. Is it required?
It's required for some sdhci variants, because issuing a command when
a card has been removed can hang (or completes after quite a long
timeout, I don't recall, Adrian?).
> Recommended? Nice to have? However, I could imagine an answer for moving
> it into the core is "no, that should be checked atomically"? E.g. sdhci
> does it, but atmel-mci and s3cmci do not. If I just look at moving the
> card detection call into the core, I don't really see the reason for
> atomic. Am I missing something?
My main concern would be performance/latency, as we would introduce
some overhead for every single request. So, no, we don't want this in
the core in my opinion.
Kind regards
Uffe
