From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Simek Subject: Re: [PATCH 2/3] spi: spi-xilinx: Clear dma_mask for xilinx spi controller Date: Wed, 05 Jun 2013 16:39:25 +0200 Message-ID: <51AF4D9D.6070808@monstr.eu> References: <041d7ca272ef9499fab630294e3395110b3e31ac.1370354549.git.michal.simek@xilinx.com> <20130604173632.GM31367@sirena.org.uk> Reply-To: monstr@monstr.eu Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="----enig2FJUXOAVGOWQCQWOJOUDC" Cc: Michal Simek , linux-kernel@vger.kernel.org, Peter Crosthwaite , Grant Likely , spi-devel-general@lists.sourceforge.net To: Mark Brown Return-path: In-Reply-To: <20130604173632.GM31367@sirena.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2FJUXOAVGOWQCQWOJOUDC Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 06/04/2013 07:36 PM, Mark Brown wrote: > On Tue, Jun 04, 2013 at 04:02:35PM +0200, Michal Simek wrote: >> From: Michal Simek >> >> mmc_spi driver tests if dma is available >> through spi->master->dev.parent->dma_mask. >> Microblaze supports DMA but xilinx_spi IP doesn't. >> That's why clear dma_mask in the driver. >=20 >> + /* clear the dma_mask, to try to disable use of dma */ >> + master->dev.dma_mask =3D 0; >> + >=20 > This looks like a bodge in the wrong place. Either the device > registration is incorrect in that it advertises DMA when none is > available or the SPI driver ought to be offering the MMC driver a more > sensible way of advertising this limitation. My first thought is the > former but I didn't check where dma_mask is getting set. I have looked at history of this change and we have done it 3 years ago based on one custom configuration. It is shame that I don't have hw to test this but there was something wrong in connection to mmc_spi.c. I will try to find out hw for this to test but probably won't be available. :-( And I will just revert this change in my tree. Thanks, Michal --=20 Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform ------enig2FJUXOAVGOWQCQWOJOUDC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlGvTaMACgkQykllyylKDCFMoQCggbK+i2sJoQYcGZ6tq5AThklh dxMAnAq2G6HAjx29MdksrH6Rlrx14uxF =FsxK -----END PGP SIGNATURE----- ------enig2FJUXOAVGOWQCQWOJOUDC--