From: broonie@kernel.org (Mark Brown) Date: Mon, 9 Apr 2018 12:27:03 +0100 Subject: [PATCH v3 3/6] spi: sun6i: restrict transfer length in PIO-mode In-Reply-To: <67c2006b-17f2-2459-e3c9-e91e3c694d8c@orpaltech.com> References: <20180405091913.ky4dnmszoobn2xry@flea> <20180405131735.GB12349@sirena.org.uk> <8159c3a5-af74-9f13-aedb-7ecc708bdff6@orpaltech.com> <20180406073441.xesojvzc3deljhoy@flea> <204e97cb-2f39-00f0-fd4e-3aa9a51f7cac@orpaltech.com> <20180409092730.2moyhl5aaktjwbyn@flea> <94a394bd-89bf-9334-c500-4cbadf4c1044@orpaltech.com> <20180409105001.GC11532@sirena.org.uk> <67c2006b-17f2-2459-e3c9-e91e3c694d8c@orpaltech.com> Message-ID: <20180409112703.GD11532@sirena.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Apr 09, 2018 at 02:10:40PM +0300, Sergey Suloev wrote: > On 04/09/2018 01:50 PM, Mark Brown wrote: > > On Mon, Apr 09, 2018 at 01:26:23PM +0300, Sergey Suloev wrote: > > > Because current implementation tries to send more than FIFO-depth of data in > > > a single call to "transfer_one" which is wrong. > > No, that's absolutely not the case. All any of these functions has to > > do is transfer whatever they were asked to, how they do it is not at all > > important to the framework. > I think you don't fully understand the issue. Let's talk about sun4i and? > sun6i SPI? drivers separately. > sun4i > 1)it is correctly declaring max_transfer_size=FIFO depth for PIO mode? but > transfer_one() function doesn't follow the declaration allowing PIO > transfers longer than FIFO depth? by just refilling FIFO using 3/4 FIFO > empty interrupt. I can definitely state here that long transfers WON'T WORK > on real hardware. I tested it and that's why I can say that. But as soon as > sun4i SPI driver? is correctly declaring max_transfer_size then "smart" > clients will work well by limiting a single transfer size to FIFO depth. I > tested it with real hardware, again. None of this is in the slightest bit related to the use of transfer_one() vs transfer_one_message(). These are all implementation details and will so far as I can tell apply equally to both APIs. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 488 bytes Desc: not available URL: