From: Boris Brezillon <boris.brezillon@bootlin.com>
To: Chuanhua Han <chuanhua.han@nxp.com>
Cc: "broonie@kernel.org" <broonie@kernel.org>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"eha@deif.com" <eha@deif.com>
Subject: Re: [PATCH 1/2] spi: spi-mem: Add the spi_set_xfer_bpw function
Date: Tue, 9 Oct 2018 12:05:22 +0200 [thread overview]
Message-ID: <20181009120522.6b2bd15a@bbrezillon> (raw)
In-Reply-To: <AM6PR04MB4357280CD4F77FCB01AB5C7097E70@AM6PR04MB4357.eurprd04.prod.outlook.com>
On Tue, 9 Oct 2018 09:52:23 +0000
Chuanhua Han <chuanhua.han@nxp.com> wrote:
> 1. In the dspi driver (spi controller), bits_per_word
> (dspi->bits_per_word = transfer->bits_per_word) passed from the upper
> layer (spi-mem.c) is used. In this way, I can only assign the
> appropriate value of transfer->bits_per_word before passing to the
> controller, that is, the controller driver does not know the value of
> bits_per_word, and it will use this value when the upper level sets
> what value is passed.
I think you're missing my point: ->bits_per_word is not what you're
looking for if what you're trying to do is use 32-bits accesses when
things are properly aligned.
> 2. As I understand, bits_per_word does not
> exist for non-byte alignment, but for the need to reserve non-byte
> transmission mode that meets the controller.
Exactly. It's an optimization you have to take care of inside your
driver. The core cannot help you with that.
> 3. In addition, now the
> XSPI of dspi cannot transfer data normally, so this problem needs to
> be solved.
I still don't understand what the problem is.
> As for the DMA transfer mode, some colleagues will study
> it.
next prev parent reply other threads:[~2018-10-09 10:05 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 7:06 [PATCH 1/2] spi: spi-mem: Add the spi_set_xfer_bpw function Chuanhua Han
2018-09-21 7:06 ` [PATCH 2/2] spi: spi-fsl-dspi: Fix support for XSPI transport mode Chuanhua Han
2018-09-28 6:37 ` Chuanhua Han
2018-09-28 6:55 ` Boris Brezillon
2018-09-29 14:56 ` Esben Haabendal
2018-09-29 15:43 ` Boris Brezillon
2018-09-30 2:49 ` Chuanhua Han
2018-09-21 7:06 ` [PATCH] spi: spi-mem: Adjust op len based on message/transfer size limitations Chuanhua Han
2018-09-21 7:15 ` Chuanhua Han
2018-09-28 6:37 ` [PATCH 1/2] spi: spi-mem: Add the spi_set_xfer_bpw function Chuanhua Han
2018-09-28 6:44 ` Boris Brezillon
2018-09-28 6:59 ` Chuanhua Han
2018-09-28 7:18 ` Boris Brezillon
2018-09-28 7:29 ` Chuanhua Han
2018-09-28 13:26 ` Mark Brown
2018-10-09 9:52 ` Chuanhua Han
2018-10-09 10:05 ` Boris Brezillon [this message]
2018-10-09 10:24 ` Chuanhua Han
2018-10-09 11:20 ` Esben Haabendal
2018-10-10 2:42 ` Chuanhua Han
2018-10-10 6:38 ` Esben Haabendal
2018-10-09 10:33 ` Mark Brown
2018-10-09 13:50 ` Esben Haabendal
2018-10-09 10:53 ` Esben Haabendal
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