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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: Mark Brown <broonie@kernel.org>, <linux-spi@vger.kernel.org>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Michael Walle <michael@walle.cc>, <linux-mtd@lists.infradead.org>,
	Julien Su <juliensu@mxic.com.tw>,
	Jaime Liao <jaimeliao@mxic.com.tw>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Boris Brezillon <boris.brezillon@collabora.com>
Subject: Re: [PATCH v7 01/14] spi: spi-mem: Fix a DTR related check in spi_mem_dtr_supports_op()
Date: Tue, 21 Dec 2021 10:50:58 +0100	[thread overview]
Message-ID: <20211221105058.69822ac5@xps13> (raw)
In-Reply-To: <20211220183917.m3mywavgxsgq7yar@ti.com>

Hi Pratyush,

p.yadav@ti.com wrote on Tue, 21 Dec 2021 00:09:19 +0530:

> On 17/12/21 05:16PM, Miquel Raynal wrote:
> > It seems that the number of command bytes must be "2" only when the
> > command itself is sent in DTR mode. The current logic checks if the
> > number of command bytes is "2" when any of the cycles is a DTR cycle. It
> > is likely that so far no device was actually mixing DTR/non-DTR cycles
> > in the same operation, explaining why this was left undetected until
> > now.  
> 
> This was intentional. spi_mem_dtr_supports_op() must only be called when 
> the operation is DTR in all phases so I did not add any sanity checks if 
> someone was using it for non-DTR ops.

Maybe that was the original intention but since then the Macronix
driver has been merged and supports (at lest does not reject) these
modes.

> In fact, I added on to this 
> function in [0] to check nbytes for other phases as well. The patch fell 
> off my radar unfortunately, and it didn't get merged.
> 
> I would like to keep this as it is since we have no user of mixed 
> DTR/non-DTR modes yet.

I don't know if the Macronix driver really supports it or if it is the
driver that is doing the wrong checks but in appearance such mixed mode
could be used.

> But if you really want to support it, please 
> apply my patch first to make sure we check for every phase, not just 
> command.
> 
> [0] https://lore.kernel.org/all/20210531181757.19458-5-p.yadav@ti.com/

Nice, I might take that as well indeed in order to make the checks a
little bit more robust.

Thanks,
Miquèl

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

WARNING: multiple messages have this Message-ID (diff)
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Pratyush Yadav <p.yadav@ti.com>
Cc: Mark Brown <broonie@kernel.org>, <linux-spi@vger.kernel.org>,
	Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tudor Ambarus <Tudor.Ambarus@microchip.com>,
	Michael Walle <michael@walle.cc>, <linux-mtd@lists.infradead.org>,
	Julien Su <juliensu@mxic.com.tw>,
	Jaime Liao <jaimeliao@mxic.com.tw>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Boris Brezillon <boris.brezillon@collabora.com>
Subject: Re: [PATCH v7 01/14] spi: spi-mem: Fix a DTR related check in spi_mem_dtr_supports_op()
Date: Tue, 21 Dec 2021 10:50:58 +0100	[thread overview]
Message-ID: <20211221105058.69822ac5@xps13> (raw)
In-Reply-To: <20211220183917.m3mywavgxsgq7yar@ti.com>

Hi Pratyush,

p.yadav@ti.com wrote on Tue, 21 Dec 2021 00:09:19 +0530:

> On 17/12/21 05:16PM, Miquel Raynal wrote:
> > It seems that the number of command bytes must be "2" only when the
> > command itself is sent in DTR mode. The current logic checks if the
> > number of command bytes is "2" when any of the cycles is a DTR cycle. It
> > is likely that so far no device was actually mixing DTR/non-DTR cycles
> > in the same operation, explaining why this was left undetected until
> > now.  
> 
> This was intentional. spi_mem_dtr_supports_op() must only be called when 
> the operation is DTR in all phases so I did not add any sanity checks if 
> someone was using it for non-DTR ops.

Maybe that was the original intention but since then the Macronix
driver has been merged and supports (at lest does not reject) these
modes.

> In fact, I added on to this 
> function in [0] to check nbytes for other phases as well. The patch fell 
> off my radar unfortunately, and it didn't get merged.
> 
> I would like to keep this as it is since we have no user of mixed 
> DTR/non-DTR modes yet.

I don't know if the Macronix driver really supports it or if it is the
driver that is doing the wrong checks but in appearance such mixed mode
could be used.

> But if you really want to support it, please 
> apply my patch first to make sure we check for every phase, not just 
> command.
> 
> [0] https://lore.kernel.org/all/20210531181757.19458-5-p.yadav@ti.com/

Nice, I might take that as well indeed in order to make the checks a
little bit more robust.

Thanks,
Miquèl

  reply	other threads:[~2021-12-21  9:52 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-17 16:16 [PATCH v7 00/14] External ECC engines & Macronix support Miquel Raynal
2021-12-17 16:16 ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 01/14] spi: spi-mem: Fix a DTR related check in spi_mem_dtr_supports_op() Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 18:39   ` Pratyush Yadav
2021-12-20 18:39     ` Pratyush Yadav
2021-12-21  9:50     ` Miquel Raynal [this message]
2021-12-21  9:50       ` Miquel Raynal
2021-12-21 10:15       ` Pratyush Yadav
2021-12-21 10:15         ` Pratyush Yadav
2021-12-17 16:16 ` [PATCH v7 02/14] spi: spi-mem: Introduce a capability structure Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 18:43   ` Pratyush Yadav
2021-12-20 18:43     ` Pratyush Yadav
2021-12-21  9:35     ` Miquel Raynal
2021-12-21  9:35       ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 03/14] spi: spi-mem: Check the controller extra capabilities Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 18:48   ` Pratyush Yadav
2021-12-20 18:48     ` Pratyush Yadav
2021-12-17 16:16 ` [PATCH v7 04/14] spi: cadence: Provide a capability structure Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 18:55   ` Pratyush Yadav
2021-12-20 18:55     ` Pratyush Yadav
2021-12-21 10:16     ` Miquel Raynal
2021-12-21 10:16       ` Miquel Raynal
2021-12-21 10:41       ` Pratyush Yadav
2021-12-21 10:41         ` Pratyush Yadav
2021-12-21 11:19         ` Miquel Raynal
2021-12-21 11:19           ` Miquel Raynal
2021-12-21 12:05           ` Pratyush Yadav
2021-12-21 12:05             ` Pratyush Yadav
2022-01-03  8:38             ` Boris Brezillon
2022-01-03  8:38               ` Boris Brezillon
2022-01-03  9:18               ` Miquel Raynal
2022-01-03  9:18                 ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 05/14] spi: mxic: " Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 06/14] spi: spi-mem: Kill the spi_mem_dtr_supports_op() helper Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 18:58   ` Pratyush Yadav
2021-12-20 18:58     ` Pratyush Yadav
2021-12-21  9:58     ` Miquel Raynal
2021-12-21  9:58       ` Miquel Raynal
2021-12-21 10:10       ` Pratyush Yadav
2021-12-21 10:10         ` Pratyush Yadav
2021-12-21 10:25         ` Miquel Raynal
2021-12-21 10:25           ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 07/14] spi: spi-mem: Add an ecc_en parameter to the spi_mem_op structure Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-20 19:02   ` Pratyush Yadav
2021-12-20 19:02     ` Pratyush Yadav
2021-12-21 17:37     ` Miquel Raynal
2021-12-21 17:37       ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 08/14] mtd: spinand: Delay a little bit the dirmap creation Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 09/14] mtd: spinand: Create direct mapping descriptors for ECC operations Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 10/14] spi: mxic: Fix the transmit path Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 11/14] spi: mxic: Create a helper to configure the controller before an operation Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 12/14] spi: mxic: Create a helper to ease the start of " Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 13/14] spi: mxic: Add support for direct mapping Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal
2021-12-17 16:16 ` [PATCH v7 14/14] spi: mxic: Add support for pipelined ECC operations Miquel Raynal
2021-12-17 16:16   ` Miquel Raynal

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