From: Peter Ujfalusi Subject: Re: [PATCH 02/13] dmaengine: Introduce dma_request_slave_channel_compat_reason() Date: Fri, 29 May 2015 17:32:50 +0300 Message-ID: <55687892.7050606@ti.com> References: <1432646768-12532-1-git-send-email-peter.ujfalusi@ti.com> <1432646768-12532-3-git-send-email-peter.ujfalusi@ti.com> <20150529093317.GF3140@localhost> <20150529101846.GG3140@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Cc: "devicetree@vger.kernel.org" , ALSA Development Mailing List , Tony Lindgren , Linux MMC List , "linux-kernel@vger.kernel.org" , linux-spi , linux-crypto@vger.kernel.org, "linux-serial@vger.kernel.org" , dmaengine@vger.kernel.org, Dan Williams , "linux-omap@vger.kernel.org" , Linux Media Mailing List To: Vinod Koul , Geert Uytterhoeven Return-path: In-Reply-To: <20150529101846.GG3140@localhost> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org List-Id: linux-crypto.vger.kernel.org On 05/29/2015 01:18 PM, Vinod Koul wrote: > On Fri, May 29, 2015 at 11:42:27AM +0200, Geert Uytterhoeven wrote: >> On Fri, May 29, 2015 at 11:33 AM, Vinod Koul wrot= e: >>> On Tue, May 26, 2015 at 04:25:57PM +0300, Peter Ujfalusi wrote: >>>> dma_request_slave_channel_compat() 'eats' up the returned error codes = which >>>> prevents drivers using the compat call to be able to do deferred probi= ng. >>>> >>>> The new wrapper is identical in functionality but it will return with = error >>>> code in case of failure and will pass the -EPROBE_DEFER to the caller = in >>>> case dma_request_slave_channel_reason() returned with it. >>> This is okay but am worried about one more warpper, how about fixing >>> dma_request_slave_channel_compat() >> >> Then all callers of dma_request_slave_channel_compat() have to be >> modified to handle ERR_PTR first. >> >> The same is true for (the existing) dma_request_slave_channel_reason() >> vs. dma_request_slave_channel(). > Good point, looking again, I think we should rather fix > dma_request_slave_channel_reason() as it was expected to return err code = and > add new users. Anyway users of this API do expect the reason... Hrm, they are for different use.dma_request_slave_channel()/_reason() is for drivers only working via DT or ACPI while dma_request_slave_channel_compat()/_reason() is for drivers expected to run= in DT/ACPI or legacy mode as well. I added the dma_request_slave_channel_compat_reason() because OMAP/daVinci drivers are using this to request channels - they need to support DT and legacy mode. But it is doable to do this for both the non _compat and _compat version: 1. change all users to check IS_ERR_OR_NULL(chan) return the PTR_ERR if not NULL, or do whatever the driver was doing in case of chan =3D=3D NULL. 2. change the non _compat and _compat versions to do the same as the _reason variants, #define the _reason ones to the non _reason names 3. Rename the _reason use to non _reason function in drivers 4. Remove the #defines for the _reason functions 5. Change the IS_ERR_OR_NULL(chan) to IS_ERR(chan) in all drivers The result: Both dma_request_slave_channel() and dma_request_slave_channel_compat() will return ERR_PTR in case of failure or in success they will return the pinter= to chan. Is this what you were asking? It is a bit broader than what this series was doing: taking care of OMAP/daVinci drivers for deferred probing regarding to dmaengine ;) -- = P=E9ter