Re: [PATCH v2] ARM: dts: imx6dl: disable dma support for spi on i.mx6dl

[Robin Gong]

On Wed, Sep 17, 2014 at 11:19:34AM +0200, Lucas Stach wrote:
> Am Mittwoch, den 17.09.2014, 17:19 +0800 schrieb Robin Gong:
> > On Wed, Sep 17, 2014 at 10:55:56AM +0200, Lucas Stach wrote:
> > > Am Mittwoch, den 17.09.2014, 16:41 +0800 schrieb Robin Gong:
> > > > On Tue, Sep 16, 2014 at 11:50:06AM +0200, Lucas Stach wrote:
> > > > > Hi Robin,
> > > > > 
> > > > > Am Dienstag, den 16.09.2014, 11:41 +0800 schrieb Robin Gong:
> > > > > > Hi Lucas,
> > > > > >   I understood your concern,but looks we have to break old DT.
> > > > > 
> > > > > Sorry, but this isn't going to happen. And honestly I don't even see the
> > > > > need to do so.
> > > > > 
> > > > > > Our old DT
> > > > > > support SPI DMA on i.mx6q/dl(v2,b3810c3dc1bcbc6a), but the DMA support patch
> > > > > > for SPI driver is still in reviewing(v6).
> > > > > 
> > > > > So this means now is the time to fix this driver patch to not enable DMA
> > > > > on imx6dl. Nobody will experience any breakage in this case.
> > > > >
> > > > Sorry, i.mx6q and i.mx6dl are totally same, not only IP but also clock. So we
> > > > can't distinguish them except for different compatible name....
> > > 
> > > I know that, but I still don't see the problem.
> > > 
> > > If this issue is specific to the ECSPI IP integrated into a imx6dl SoC
> > > you need to check for the machine compatible in the driver and disable
> > > DMA support based on this. We generally avoid checking for the machine
> > > compatible in drivers and prefer to have a specific IP block compatible
> > > instead, but in that case it's the only reasonable thing to do.
> > > 
> > > Regards,
> > > Lucas
> > Sounds we make a agreement on use different compatible name, right? I will
> > make patch for reviewing, thanks.
> 
> No you can't use a new compatible name for the IP block, as this again
> would only fix things for users with new devicetrees. Also this has
> nothing to do with the IP block, but is an integration issue between
> ECPSI and imx6dl.
> 
> So what you need to do is something like this in the ecspi kernel
> driver:
> 
> if (of_machine_is_compatible("fsl,imx6dl") {
>     do_whatever_is_necessary_to_make_sure_DMA_is_not_enabled();
> }
> 
> Regards,
> Lucas
Sure, the ecspi kernel driver must check the new compatible name for i.mx6dl.
> -- 
> Pengutronix e.K.             | Lucas Stach                 |
> Industrial Linux Solutions   | http://www.pengutronix.de/  |
> 
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