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Date:   Fri, 17 Sep 2021 07:10:26 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Huacai Chen <chenhuacai@loongson.cn>
Cc:     Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
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        Huacai Chen <chenhuacai@gmail.com>,
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Subject: Re: [PATCH V3 16/22] LoongArch: Add misc common routines
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References: <20210917035736.3934017-1-chenhuacai@loongson.cn>
 <20210917035736.3934017-17-chenhuacai@loongson.cn>
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> +
> +/*
> + * Change "struct page" to physical address.
> + */
> +#define page_to_phys(page)	((dma_addr_t)page_to_pfn(page) << PAGE_SHIFT)

Why is this using a dma_addr_t?  phys_addr_t would be the right type
here.

> +
> +extern void __init __iomem *early_ioremap(u64 phys_addr, unsigned long size);
> +extern void __init early_iounmap(void __iomem *addr, unsigned long size);
> +
> +#define early_memremap early_ioremap
> +#define early_memunmap early_iounmap
> +
> +static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
> +					 unsigned long prot_val)
> +{
> +	if (prot_val == _CACHE_CC)
> +		return (void __iomem *)(unsigned long)(CAC_BASE + offset);
> +	else
> +		return (void __iomem *)(unsigned long)(UNCAC_BASE + offset);
> +}

There is no real need for this ioremap_prot multiplexer

> +/*
> + * ioremap_cache -  map bus memory into CPU space
> + * @offset:	    bus address of the memory
> + * @size:	    size of the resource to map
> + *
> + * ioremap_cache performs a platform specific sequence of operations to
> + * make bus memory CPU accessible via the readb/readw/readl/writeb/
> + * writew/writel functions and the other mmio helpers. The returned
> + * address is not guaranteed to be usable directly as a virtual
> + * address.
> + *
> + * This version of ioremap ensures that the memory is marked cachable by
> + * the CPU.  Also enables full write-combining.	 Useful for some
> + * memory-like regions on I/O busses.
> + */
> +#define ioremap_cache(offset, size)				\
> +	ioremap_prot((offset), (size), _CACHE_CC)

Please don't add ioremap_cache to new ports.