Re: [PATCH 1/3] spi: spi-mem: add automatic poll status functions

From: Mark Brown <broonie@kernel.org>
To: Patrice CHOTARD <patrice.chotard@foss.st.com>
Cc: Pratyush Yadav <p.yadav@ti.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	linux-mtd@lists.infradead.org,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	linux-spi@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, christophe.kerello@foss.st.com
Subject: Re: [PATCH 1/3] spi: spi-mem: add automatic poll status functions
Date: Fri, 30 Apr 2021 16:56:23 +0100	[thread overview]
Message-ID: <20210430155623.GD5981@sirena.org.uk> (raw)
In-Reply-To: <28acedfd-6cd5-a8ad-0182-e61c3c30c27d@foss.st.com>

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On Fri, Apr 30, 2021 at 04:22:34PM +0200, Patrice CHOTARD wrote:
> On 4/26/21 6:51 PM, Mark Brown wrote:
> > On Mon, Apr 26, 2021 at 09:56:12PM +0530, Pratyush Yadav wrote:

> > Is it possible there's some situation where you're waiting for some bits
> > to clear as well?

> Yes, we are waiting STATUS_BUSY bit to be cleared, see patch 2 which is making 
> usage of this API.

Then the inverse question applies - is there no circumstance where we
might be waiting for a bit to be set?

> > We already have the core handling other timeouts.  We don't pass around
> > completions but rather have an API function that the driver has to call
> > when the operation completes, a similar pattern might work here.  Part

> So, if i correctly understood, you make allusion to what is already done
> in SPI core framework with spi_finalize_current_transfer() right ?

Yes, and _current_message().

> > of the thing with those APIs which I'm missing here is that this will
> > just return -EOPNOTSUPP if the driver can't do the delay in hardware, I
> > think it would be cleaner if this API were similar and the core dealt
> > with doing the delay/poll on the CPU.  That way the users don't need to
> > repeat the handling for the offload/non-offload cases.

> Sorry, i didn't catch what you mean here. In PATCH 2, that's the case,
> if spi_mem_poll_status() is not supported, the core is dealing with 
> the delay/poll on the CPU in spinand_wait().

That's in the NAND core, not in spi-mem.  Any other users of spi-mem
will also need to open code stuff.

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