linux-kernel - Re: [PATCH 1/2] spi: cadence-quadspi: Disable Auto-HW polling

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Message-ID: <20210716180452.GD4137@sirena.org.uk>
Date:   Fri, 16 Jul 2021 19:04:52 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Pratyush Yadav <p.yadav@...com>
Cc:     Apurva Nandan <a-nandan@...com>, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH 1/2] spi: cadence-quadspi: Disable Auto-HW polling

On Fri, Jul 16, 2021 at 12:06:29AM +0530, Pratyush Yadav wrote:
> On 15/07/21 05:41PM, Mark Brown wrote:
> > On Thu, Jul 15, 2021 at 09:57:51PM +0530, Apurva Nandan wrote:

> But then the problem is how to tell the caller whether the poll actually 
> happened or not. The other option I see is:

>   ret = spi_mem_set_autopoll_op(mem, poll_op, mask, match, ...);
>   spi_mem_exec_op(mem, op);
> 
>   if (ret == -EOPNOTSUPP)
> 	poll_status();

> When spi_mem_set_autopoll_op() is called, the controller driver can 
> check if it can autopoll with this op. It can configure its autopoll 
> feature based on this, and can provide feedback to the caller about 
> whether they will then have to poll themselves, or it has already been 
> done for them.

I was more thinking about just having polling be a separate operation
entirely, but you're right that a controller might integrate polling
with the actual operation so that won't do and we need something more
like you suggest.

> I like the latter option more.

Yes.

> I think the question we need to answer first is whether doing all this 
> is worth the hassle. Are there enough controllers with this auto polling 
> feature to make it worth the bother?

If we build it they will come! :P  But yes, that's definitely a concern.

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