On Thu, Apr 27, 2023, at 08:22, Thomas Zimmermann wrote: > Am 26.04.23 um 21:21 schrieb Sam Ravnborg: >> On Wed, Apr 26, 2023 at 03:04:15PM +0200, Thomas Zimmermann wrote: >>> Fbdev provides helpers for framebuffer I/O, such as fb_readl(), >>> fb_writel() or fb_memcpy_to_fb(). The implementation of each helper >>> depends on the architecture. It's still all located in fbdev's main >>> header file <linux/fb.h>. Move all of it into each archtecture's >>> <asm/fb.h>, with shared code in <asm-generic/fb.h>. >> >> For once I think this cleanup is moving things in the wrong direction. >> >> The fb_* helpers predates the generic io.h support and try to >> add a generic layer for read read / write operations. >> >> The right fix would be to migrate fb_* to use the io helpers >> we have today - so we use the existing way to handle the architecture >> specific details. > > I looked through the existing versions of the fb_() I/O helpers. They > can apparently be implemented with the regular helpers of similar names. > > I'm not sure, but even Sparc looks compatible. At least these sbus_ > functions seem to be equivalent to the __raw_() I/O helpers of similar > names. Do you still have that Sparc emulator? I looked at the current code and came to the same conclusion: all architectures we support today do the same thing in __raw_readl() and fb_readl() etc, so we can completely remove the latter without changing semantics. I think the original list was necessary since not all architectures supported the __raw_ accessors in the past, so they were open-coded here for the rest. I thought there were also architectures on which __raw_readl() does a byteswap to reverse the swap done in a PCI host bridge, but it apears that none of those remain now, if we ever had them. Arnd
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