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:[email protected]] >> Sent: Wednesday, April 27, 2016 6:10 PM >> To: Appana Durga Kedareswara Rao <[email protected]>; >> [email protected]; [email protected]; [email protected]; >> [email protected]; [email protected]; Michal Simek >> <[email protected]>; Soren Brinkmann <[email protected]>; >> [email protected]; [email protected]; [email protected]; >> [email protected]; [email protected]; Anirudha >> Sarangi <[email protected]>; Punnaiah Choudary Kalluri >> <[email protected]> >> Cc: [email protected]; [email protected]; linux- >> [email protected]; [email protected] >> 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:[email protected]] >>>> Sent: Wednesday, April 27, 2016 12:42 PM >>>> To: Appana Durga Kedareswara Rao <[email protected]>; >>>> [email protected]; [email protected]; [email protected]; >>>> [email protected]; [email protected]; Michal Simek >>>> <[email protected]>; Soren Brinkmann <[email protected]>; >>>> [email protected]; [email protected]; Appana Durga >>>> Kedareswara Rao <[email protected]>; [email protected]; >>>> [email protected]; [email protected]; Anirudha >>>> Sarangi <[email protected]>; Punnaiah Choudary Kalluri >>>> <[email protected]> >>>> Cc: [email protected]; [email protected]; >>>> linux- [email protected]; [email protected] >>>> 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.
