Hi Boris, > -----Original Message----- > From: Boris Brezillon [mailto:[email protected]] > Sent: Tuesday, August 21, 2018 11:30 AM > To: Naga Sureshkumar Relli <[email protected]> > Cc: [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > linux- > [email protected]; [email protected]; Michal Simek > <[email protected]>; > [email protected] > Subject: Re: [LINUX PATCH v10 1/2] dt-bindings: mtd: arasan: Add device tree > binding > documentation > > On Tue, 21 Aug 2018 05:47:18 +0000 > Naga Sureshkumar Relli <[email protected]> wrote: > > > > > +Required properties: > > > > +- compatible: Should be "xlnx,zynqmp-nand" or > > > > "arasan,nfc-v3p10" > > > > > > In your example it's not an "or" since both are defined. > > In our previous discussion > > (https://lore.kernel.org/patchwork/patch/748901/) > > We decided to have compatible strings like " compatible = > > "<soc-vendor>,<ip-revision>", > "arasan,<ip-revision>";" > > So it should be either of these. > > so I will write something like below > > "Possible values are "xlnx,zynqmp-nand" > > "arasan,nfc-v3p10" > > And in example I will mention any one compatible. > > Is it ok? > > Hm, why do you need arasan,nfc-v3p10 at all if it's supposed to be overloaded > by a soc specific > compat? Actually we put these compatible strings based on the comments on v7 series. Anyway I will just keep "xlnx,zynqmp-nand" as compatible. > > > > > + > > > > +Optional properties: > > > > +- arasan,has-mdma: Enables DMA support > > > > > > Can't you detect that based on the compatible (or thanks to a > > > register). If it's something you choose when configuring the IP and can't > > > detect at > runtime I guess it's fine. > > There is no way to select DMA when configuring the IP. > > But it has internal DMA and there is a register to select PIO or DMA while > > starting a > transfer. > > So if user really don't want DMA, then we will never set DMA in the code > > based on DT > property. > > If it's a purely SW choice, then is shouldn't be described in the DT. > You can use a module param, but I'm not even sure why one would want to > disable DMA. UBIFS doesn't work with DMA, hence we are using a DT property to operate the driver in IO. But as you pointed (use virt_is_valid()), with this we can switch our driver to operate in PIO or DMA. I will remove this from DT.
Thanks, Naga Sureshkumar Relli.
