linux-kernel - RE: [PATCH v2 6/6] mtd: spi-nor: core: avoid odd length/address writes in 8D-8D-8D mode

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Message-ID:
 <DU0PR04MB9496CB86FFAA35002A9B6B3D9097A@DU0PR04MB9496.eurprd04.prod.outlook.com>
Date: Mon, 12 May 2025 08:33:46 +0000
From: Bough Chen <haibo.chen@....com>
To: Miquel Raynal <miquel.raynal@...tlin.com>, Pratyush Yadav
	<pratyush@...nel.org>
CC: Tudor Ambarus <tudor.ambarus@...aro.org>, Luke Wang
	<ziniu.wang_1@....com>, "broonie@...nel.org" <broonie@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>, "michael@...le.cc"
	<michael@...le.cc>, "p.yadav@...com" <p.yadav@...com>, "richard@....at"
	<richard@....at>, "vigneshr@...com" <vigneshr@...com>, Han Xu
	<han.xu@....com>
Subject: RE: [PATCH v2 6/6] mtd: spi-nor: core: avoid odd length/address
 writes in 8D-8D-8D mode

> -----Original Message-----
> From: Miquel Raynal <miquel.raynal@...tlin.com>
> Sent: 2025年5月12日 15:57
> To: Pratyush Yadav <pratyush@...nel.org>
> Cc: Tudor Ambarus <tudor.ambarus@...aro.org>; Luke Wang
> <ziniu.wang_1@....com>; broonie@...nel.org; linux-kernel@...r.kernel.org;
> linux-mtd@...ts.infradead.org; linux-spi@...r.kernel.org; michael@...le.cc;
> p.yadav@...com; richard@....at; vigneshr@...com; Bough Chen
> <haibo.chen@....com>; Han Xu <han.xu@....com>
> Subject: Re: [PATCH v2 6/6] mtd: spi-nor: core: avoid odd length/address writes
> in 8D-8D-8D mode
> 
> Hello,
> 
> On 07/05/2025 at 09:43:25 GMT, Pratyush Yadav <pratyush@...nel.org>
> wrote:
> 
> > Hi Luke,
> >
> > On Tue, Apr 29 2025, Tudor Ambarus wrote:
> >
> >> On 4/29/25 10:03 AM, Luke Wang wrote:
> >>> Hi Pratyush,
> >>>
> >>> I'm following up on this patch series [1] Avoid odd length/address
> >>> read/ writes in 8D-8D-8D mode. While some of the series has been
> >>> merged, the patch 4-6 remains unmerged.
> >>>
> >>> In fact, we also encountered similar read/write issue of odd
> >>> address/ length with NXP FSPI controller (spi-nxp-fspi.c).
> >>> Currently, we handled the odd address/length in the controller
> >>> driver, but I think this should be a common issue in the octal dtr
> >>> mode. Was there a technical reason for not merging the core layer
> solution?
> >>
> >> I guess I stumbled on those small comments and did not consider the
> >> greater benefit of taking the patches. No one cared and we forgot
> >> about it. Please address the comments and resubmit.
> >
> > Yes, it should have been a simple next revision from me but apparently
> > it fell through the cracks. I do strongly agree that this should be
> > done in SPI NOR, and not in controller drivers. So it would be great
> > if you can respin the remaining patches of the series.
> 
> The fact is that we will have octal DTR support in SPI NAND as well at some
> point, hence a common solution would be welcome as we will likely face similar
> problems when performing these unaligned accesses. I don't know how feasible
> it is yet, but if we have a fix for SPI NOR, we will need something similar for SPI
> NAND.

Currently for octal DTR SPI NAND, seems do not support 8D-8D-8D, I check winbond, only support 1S-1D-8D mode. SPI NAND and SPI NOR share spi-mem.c, and in spi-mem.c, spi_mem_default_supports_op(), for DTR mode, the command must be DTR, so do not support 1S-1D-8D mode. This is the problem I can see.

We have local patch to handle the odd/even length/address in flexspi driver, I will prepare to move these to spi-nor core and send out for review first, but for SPI-NAND DTR mode, may need further efforts.

Regards
Haibo Chen 
> 
> Thanks,
> Miquèl