From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Balbi Subject: Re: [RFC PATCH 08/13] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC Date: Fri, 21 Sep 2012 20:18:41 +0300 Message-ID: <20120921171840.GB10409@arwen.pp.htv.fi> References: <1348152226-13588-1-git-send-email-mporter@ti.com> <1348152226-13588-9-git-send-email-mporter@ti.com> Reply-To: balbi@ti.com Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="KFztAG8eRSV9hGtP" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org To: "S, Venkatraman" Cc: Matt Porter , Tony Lindgren , Sekhar Nori , Grant Likely , Mark Brown , Benoit Cousson , Russell King , Vinod Koul , Rob Landley , Chris Ball , Linux DaVinci Kernel List , Arnd Bergmann , Linux Documentation List , Devicetree Discuss , Linux MMC List , Linux Kernel Mailing List , Rob Herring , Dan Williams , Linux SPI Devel List , Linux OMAP List Linux List-Id: devicetree@vger.kernel.org --KFztAG8eRSV9hGtP Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Sep 21, 2012 at 10:47:30PM +0530, S, Venkatraman wrote: > On Fri, Sep 21, 2012 at 10:45 PM, S, Venkatraman wrote: > > On Thu, Sep 20, 2012 at 8:13 PM, Matt Porter wrote: > >> The EDMA DMAC has a hardware limitation that prevents supporting > >> scatter gather lists with any number of segments. Since the EDMA > >> DMA Engine driver sets the maximum segments to 16, we do the > >> same. > >> > >> Note: this can be removed once the DMA Engine API supports an > >> API to query the DMAC's segment limitations. > >> > > > > I wouldn't want to bind the properties of EDMA to omap_hsmmc as this pa= tch > > suggests. Why don't we have a max_segs property, which when explicitly = specified > > in DT, will override the default ? >=20 > If you are adventurous, this can be a generic mmc DT binding instead > of restricting it to OMAP. I say if it's a limitation in the DMAC, then DMAC's driver should handle it, no ? Meaning that in this case you would copy from one multi-segment sg into a one-segment sg and when transfer is complete, before calling user's callback, copy data the other way around (?) --=20 balbi --KFztAG8eRSV9hGtP Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJQXKFwAAoJEIaOsuA1yqREWTUP/10iBfr1wNrAWCDghpd4U6dl wDjgM4HgNKsrYRl3uMn+NShEjYNyPSxtETSmODVUbSU2wo3h/AVuo/LLQwJhcHCY dQoF/h3Az2uEaJGZdfnwU48zv9SnQ/X//ZTstaSRzjZDkrC/WRPYiqmMtScgyklU qvnF+BS7mNn+MHjQk5b8QsRUi8nk4rCiUlh3AouAhUlekPXPXkM3KF2PDEgin+9e GKYu+8bMRy4w2/qbB2cSSCGNxVIfk250V8aAZfZ1vqNmGOMN7tD9F6qEZJYuq6OZ aHHaumkj+KptFOjXlfk3mL1Q5sTgMMZRC5ZZXBzRlILl8H0NW0ghXTvQyqnX2Y2V J7u1D11vXAQkgTSfzSr2JK7WXy9KYTnL82E/LsZhBmxrEGEVfPGGf97pKD7okt90 NYqF0PzR3CE6S7GPwBccjJwcBsusaT23+fXNS70GaWVqH8e+eUxDTubIak4ThNZC MEqvjEXCNR6CDDa4L3JBdRFl9E1BQ5H1OvGKLHvxDItbSh3TTPHQCxjlaspGL2oW CWaPAoZTF0EajhSN7zYHZFW8TzxYdY5sCcFOpY475myucPs2q/UonzDd6VHwurah nINkgLb1H7HhnCdgbSHDvqbxB/a4yzCny2lJmWL5zYATVJL1g3uPsVhtVX4cz70u Nj0JmrafhJRUR8v5flxs =09if -----END PGP SIGNATURE----- --KFztAG8eRSV9hGtP--