On 04/28/2016 11:00 AM, Appana Durga Kedareswara Rao wrote: > 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. Sorry, but that is just as broken. You need to derive those parameters from the DMA transfer as they are transfer specific. -- 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
