From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH v4 2/4] spi: Split spi message into max_dma_len size chunks Date: Fri, 12 Apr 2019 11:22:07 +0100 Message-ID: <20190412102206.GG6909@sirena.org.uk> References: <20190411164235.49771-1-noralf@tronnes.org> <20190411164235.49771-3-noralf@tronnes.org> <20190411181836.t2vuutqhjglsxsaz@wunner.de> <98571639-840a-494c-9e41-29ff89a22a8e@tronnes.org> <20190412094721.GE6909@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1867558378==" Cc: Stefan Wahren , dri-devel@lists.freedesktop.org, linux-spi , linux-rpi-kernel , meghana.madhyastha@gmail.com To: kernel@martin.sperl.org Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" List-Id: linux-spi.vger.kernel.org --===============1867558378== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="t4apE7yKrX2dGgJC" Content-Disposition: inline --t4apE7yKrX2dGgJC Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Apr 12, 2019 at 12:03:35PM +0200, kernel@martin.sperl.org wrote: > > On 12.04.2019, at 11:47, Mark Brown wrote: > >> In a previous version of this I suggested to Meghana to put this in the > >> driver, but Mark wanted it in the core. > > If we want to do this at a lower level the DMA code could hide this > > limitation from the upper layers; presumably the SPI driver isn't the > > only thing that might run into this. > For clarification: > There is a register of the SPI controller where you have to configure the > number of bytes that it will request via DMA (primarily support transfers > that are not a multiple of 4 - the data is transferred by DMA as words). > So it is not really related to the general DMA implementation but to the > DMA (request) support of the SPI controller. Ah, I see. That's unfortunate :/ --t4apE7yKrX2dGgJC Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlywZs4ACgkQJNaLcl1U h9B/PQf/RSTE5q9iKH4n63hVRffjLEbGYFvapmk+unzydgHkjPokTJT890QulO5i ShuaPXy+rGMZ0kXjIXGFNVgefkwBHmoYKanS8XIpUcRoiGOGaWOhqtJwuTn4peTw ZsD1vplBImTTkbvsM+g4zEltWXZN/wuIzrd4E3cPMqC4oPCsrzaAnBG6fXpj44M/ aQu3nvLOV4A8w9BMEqEXKHRcFf032JR1FXAfURdol7Hv2+7rem9sRBDJpDbWYhip TiNJsOfJW60pIy8a6+37DTaKFD1f0EQxWyxPHx/2c7ZT4QCaqTXfVXEI+ZDLLsAt snjY4FjAWfqrusFuWZkNyRNIRl31fQ== =Pkgq -----END PGP SIGNATURE----- --t4apE7yKrX2dGgJC-- --===============1867558378== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVs IG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlz dHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVs --===============1867558378==--