Hi everybody The MVPP2 code already has DMA's patch taken from OLD Backport and placed by Antoine Tenart. Please refer the attached Best regards Yan Markman -----Original Message----- From: Christoph Hellwig [mailto:hch@infradead.org] Sent: Monday, August 20, 2018 9:23 AM To: David Miller Cc: brian.brooks@linaro.org; antoine.tenart@bootlin.com; maxime.chevallier@bootlin.com; Yan Markman ; Stefan Chulski ; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; bjorn.topel@intel.com; brian.brooks@arm.com Subject: Re: [PATCH] net: mvpp2: avoid bouncing buffers On Sun, Aug 19, 2018 at 07:55:05PM -0700, David Miller wrote: > From: Brian Brooks > Date: Sun, 19 Aug 2018 21:47:30 -0500 > > > @@ -5126,6 +5126,12 @@ static int mvpp2_probe(struct platform_device *pdev) > > } > > > > if (priv->hw_version == MVPP22) { > > + /* Platform code may have set dev->dma_mask to point > > + * to dev->coherent_dma_mask, but we want to ensure > > + * they take different values due to comment below. > > + */ > > + pdev->dev.dma_mask = &priv->dma_mask; > > The platform code might be doing this exactly because it cannot > support different coherent and streaming DMA masks. > > Well, in any case, the platform code is doing it for a reason and > overriding this in a "driver" of all places seems totally > inappropriate and at best a layering violation. > > I would rather you fix this in a way that involves well defined APIs > that set the DMA masks or whatever to the values that you need, rather > than going behind the platform code's back and changing the DMA mask > pointer like this. Agreed. What platform do you see this issue on?