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Date: Sun, 30 Sep 2018 01:04:16 +0800
From: Guo Ren <ren_guo@c-sky.com>
Subject: Re: [PATCH V6 07/33] csky: MMU and page table management
Message-ID: <20180929170415.GD27796@guoren-Inspiron-7460>
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To: Christoph Hellwig <hch@infradead.org>
Cc: akpm@linux-foundation.org, arnd@arndb.de, daniel.lezcano@linaro.org, davem@davemloft.net, gregkh@linuxfoundation.org, jason@lakedaemon.net, marc.zyngier@arm.com, mark.rutland@arm.com, mchehab+samsung@kernel.org, peterz@infradead.org, robh@kernel.org, robh+dt@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, devicetree@vger.kernel.org, green.hu@gmail.com
Message-ID: <20180929170416._3FyKyKyibtaZuWfxwT1htYE8QCiazpWUhRyLVeEpNg@z>

On Thu, Sep 27, 2018 at 08:47:33AM -0700, Christoph Hellwig wrote:
> > +static void *csky_dma_alloc_atomic(
> > +	struct device *dev,
> > +	size_t size,
> > +	dma_addr_t *dma_handle
> > +	)
> 
> Can you please use normal kernel coding style?  Closing brace on the
> same line, either two tab indents for the arguments or align them to the
> first argument:
> 
> static void *csky_dma_alloc_atomic(struct device *dev, size_t size,
> 		dma_addr_t *dma_handle)
> 
> or:
> 
> static void *csky_dma_alloc_atomic(struct device *dev, size_t size,
> 				   dma_addr_t *dma_handle)
OK, I like 2th.

> > +	if (DMA_ATTR_NON_CONSISTENT & attrs)
> > +		BUG();
> 
> Please don't bug on unknown attributs, they can be safely ignored.
No BUG(), return NULL.

> 
> > +void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
> > +			      size_t size, enum dma_data_direction dir)
> > +{
> > +	struct page *page = pfn_to_page(paddr >> PAGE_SHIFT);
> > +	unsigned long offset = paddr & ~PAGE_MASK;
> > +	unsigned long vaddr;
> > +
> > +	if (PageHighMem(page))
> > +		vaddr = (unsigned long) kmap_atomic(page);
> 
> This isn't going to work as the size might be larger than PAGE_SIZE.
Ops ... BIG BUG, must be fixed immediately, thank you.

Best Regards
 Guo Ren