From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by canuck.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1QbuCa-0005yH-EH for linux-mtd@lists.infradead.org; Wed, 29 Jun 2011 12:49:09 +0000 Date: Wed, 29 Jun 2011 14:49:02 +0200 From: Wolfram Sang To: Russell King - ARM Linux Subject: Re: [PATCH v7 1/3] MTD : add the common code for GPMI-NFC controller driver Message-ID: <20110629124902.GI1992@pengutronix.de> References: <1309335878-16678-1-git-send-email-b32955@freescale.com> <1309335878-16678-2-git-send-email-b32955@freescale.com> <20110629100658.GE1992@pengutronix.de> <20110629103337.GF1992@pengutronix.de> <4E0B0296.6060902@freescale.com> <20110629122942.GH1992@pengutronix.de> <20110629124214.GN21898@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PWfwoUCx3AFJRUBq" Content-Disposition: inline In-Reply-To: <20110629124214.GN21898@n2100.arm.linux.org.uk> Cc: dedekind1@gmail.com, thierry.nolf.barco@gmail.com, Huang Shijie , linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, LW@KARO-electronics.de List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --PWfwoUCx3AFJRUBq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 29, 2011 at 01:42:14PM +0100, Russell King - ARM Linux wrote: > On Wed, Jun 29, 2011 at 02:29:42PM +0200, Wolfram Sang wrote: > >=20 > > > > Still, the problem exists: When a second channel GPMI channel is > > > > requested, dmaengine will return -EBUSY, because the DMAIRQ is alre= ady > > > > taken. > > > > > > > Yes, we should change the DMA code, it is a DMA bug. > > > I ever submitted a patch about the issue: > > > http://patchwork.ozlabs.org/patch/87145/ > >=20 > > That approach was rejected because it would register the same handler > > n-times where one time would do. Your other approach puts too much > > mach-specific details into the driver IMO and probably won't scale very > > well. Maybe we should add something to the private dma_data (like flags > > indicating SHARED) and then do some refcounting? >=20 > Why not just request the interrupt once when the mxs-dma stuff probes, > rather than requesting it every time a channel is allocated? It is only the NAND DMA channels which share one dma-irq. All other channels have a seperate interrupt. --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --PWfwoUCx3AFJRUBq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAk4LHz4ACgkQD27XaX1/VRvzhQCghIlFByP/19J627O2V48zpjew APIAoL9RNr6NawqhAt6qO2T6yXMzNTEv =P3yr -----END PGP SIGNATURE----- --PWfwoUCx3AFJRUBq-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: w.sang@pengutronix.de (Wolfram Sang) Date: Wed, 29 Jun 2011 14:49:02 +0200 Subject: [PATCH v7 1/3] MTD : add the common code for GPMI-NFC controller driver In-Reply-To: <20110629124214.GN21898@n2100.arm.linux.org.uk> References: <1309335878-16678-1-git-send-email-b32955@freescale.com> <1309335878-16678-2-git-send-email-b32955@freescale.com> <20110629100658.GE1992@pengutronix.de> <20110629103337.GF1992@pengutronix.de> <4E0B0296.6060902@freescale.com> <20110629122942.GH1992@pengutronix.de> <20110629124214.GN21898@n2100.arm.linux.org.uk> Message-ID: <20110629124902.GI1992@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jun 29, 2011 at 01:42:14PM +0100, Russell King - ARM Linux wrote: > On Wed, Jun 29, 2011 at 02:29:42PM +0200, Wolfram Sang wrote: > > > > > > Still, the problem exists: When a second channel GPMI channel is > > > > requested, dmaengine will return -EBUSY, because the DMAIRQ is already > > > > taken. > > > > > > > Yes, we should change the DMA code, it is a DMA bug. > > > I ever submitted a patch about the issue: > > > http://patchwork.ozlabs.org/patch/87145/ > > > > That approach was rejected because it would register the same handler > > n-times where one time would do. Your other approach puts too much > > mach-specific details into the driver IMO and probably won't scale very > > well. Maybe we should add something to the private dma_data (like flags > > indicating SHARED) and then do some refcounting? > > Why not just request the interrupt once when the mxs-dma stuff probes, > rather than requesting it every time a channel is allocated? It is only the NAND DMA channels which share one dma-irq. All other channels have a seperate interrupt. -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: