Hi Lars, Thanks for the review... > -----Original Message----- > From: Lars-Peter Clausen [mailto:lars@xxxxxxxxxx] > Sent: Wednesday, April 27, 2016 6:10 PM > To: Appana Durga Kedareswara Rao <appanad@xxxxxxxxxx>; > robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx; mark.rutland@xxxxxxx; > ijc+devicetree@xxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxx; Michal Simek > <michals@xxxxxxxxxx>; Soren Brinkmann <sorenb@xxxxxxxxxx>; > vinod.koul@xxxxxxxxx; dan.j.williams@xxxxxxxxx; moritz.fischer@xxxxxxxxx; > laurent.pinchart@xxxxxxxxxxxxxxxx; luis@xxxxxxxxxxxxxxxxx; Anirudha > Sarangi <anirudh@xxxxxxxxxx>; Punnaiah Choudary Kalluri > <punnaia@xxxxxxxxxx> > Cc: devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v7 1/2] Documentation: DT: dma: Add Xilinx zynqmp dma > device tree binding documentation > > On 04/27/2016 09:33 AM, Appana Durga Kedareswara Rao wrote: > > Hi Lars, > > > >> -----Original Message----- > >> From: Lars-Peter Clausen [mailto:lars@xxxxxxxxxx] > >> Sent: Wednesday, April 27, 2016 12:42 PM > >> To: Appana Durga Kedareswara Rao <appanad@xxxxxxxxxx>; > >> robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx; mark.rutland@xxxxxxx; > >> ijc+devicetree@xxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxx; Michal Simek > >> <michals@xxxxxxxxxx>; Soren Brinkmann <sorenb@xxxxxxxxxx>; > >> vinod.koul@xxxxxxxxx; dan.j.williams@xxxxxxxxx; Appana Durga > >> Kedareswara Rao <appanad@xxxxxxxxxx>; moritz.fischer@xxxxxxxxx; > >> laurent.pinchart@xxxxxxxxxxxxxxxx; luis@xxxxxxxxxxxxxxxxx; Anirudha > >> Sarangi <anirudh@xxxxxxxxxx>; Punnaiah Choudary Kalluri > >> <punnaia@xxxxxxxxxx> > >> Cc: devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > >> linux- kernel@xxxxxxxxxxxxxxx; dmaengine@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH v7 1/2] Documentation: DT: dma: Add Xilinx zynqmp > >> dma device tree binding documentation > >> > >> On 04/27/2016 09:05 AM, Kedareswara rao Appana wrote: > >> [...] > >>> +- xlnx,include-sg : Indicates the controller to operate in simple or > >>> + scatter gather dma mode > >>> +- xlnx,ratectrl : Scheduling interval in terms of clock cycles for > >>> + source AXI transaction > >>> +- xlnx,overfetch : Tells whether the channel is allowed to over > >>> + fetch the data > >>> +- xlnx,src-issue : Number of AXI outstanding transactions on source > >> side > >>> +- xlnx,src-burst-len : AXI length for data read. Support only power of > >>> + 2 byte values. > >>> +- xlnx,dst-burst-len : AXI length for data write. Support only power of > >> > >> These are all software runtime configuration parameters that you'd > >> want to change at runtime depending on which peripheral you are > >> targeting with a specific DMA transfer. These really do not belong into the > devicetree. > > > > You mean to have a separate config structure in the driver and handle > > the above parameters Through that structure??? > > > > I understand that above will work for slave dma transfer types what > > about memory to memory Transfers where we don't have provision to the use > this parameters... > > These parameters are just as application specific as e.g. the DMA > source/destination address or the DMA transfer length. If you want to use the > DMA controller in a different configuration you'd have to re-compile the DTB > and reboot your board, that is not really practical. Especially considering that > you'd typically have multiple applications using the DMA controller in different > configurations concurrently. In general if I have to reconfigure the DT depending > on what application software is running something is fundamentally broken. > > Derive these parameters at runtime depending on the requested transfer. E.g. > some transfer types only work in SG mode, others only work in non-SG modes. > For those which can work in both modes choose the one that is more efficient. > Similar for the other parameters. Ok will fix in the next version... Will use module_params for the above properties. Regards, Kedar. > > - Lars -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
