Re: [PATCH 06/19] mmc: cb710: Inform the mmc core about the maximum busy timeout

["Michał Mirosław" <mirq-linux@rere.qmqm.pl>]

On Tue, Apr 14, 2020 at 06:14:00PM +0200, Ulf Hansson wrote:
> Some commands uses R1B responses, which means the card may assert the DAT0
> line to signal busy for a period of time, after it has received the
> command. The mmc core normally specifies the busy period for the command in
> the cmd->busy_timeout. Ideally the driver should respect it, but that
> requires quite some update of the code, so let's defer that to someone with
> the HW at hand.
> 
> Instead, let's inform the mmc core about the maximum supported busy timeout
> in ->max_busy_timeout during ->probe(). This value corresponds to the fixed
> ~2s timeout of the polling loop, implemented in cb710_wait_for_event(). In
> this way, we let the mmc core validate the needed timeout, which may lead
> to that it converts from a R1B into a R1 response and then use CMD13 to
> poll for busy completion.
> 
> In other words, this change enables support for commands with longer busy
> periods than 2s, like erase (CMD38) for example.
[...]
> +	/*
> +	 * In cb710_wait_for_event() we use a fixed timeout of ~2s, hence let's
> +	 * inform the core about it. A future improvement should instead make
> +	 * use of the cmd->busy_timeout.
> +	 */
[...]

I'm not sure whether the controller limits busy signalling time.
Since this is rare HW now, I would just pass the timeout to
cb710_wait_for_event() and see if someone reports a bug.

Best Regards,
Michał Mirosław