On Tuesday 26 August 2014 11:08:11 Thierry Reding wrote: > On Tue, Aug 26, 2014 at 10:09:25AM +0200, Arnd Bergmann wrote: > > On Tuesday 26 August 2014 09:50:25 Thierry Reding wrote: > > > On Tue, Aug 26, 2014 at 09:43:50AM +0200, Arnd Bergmann wrote: > > > > On Tuesday 26 August 2014 08:57:31 Thierry Reding wrote: > > > > > On Mon, Aug 25, 2014 at 01:01:52PM -0600, Stephen Warren wrote: > > > > > > On 08/18/2014 11:08 AM, Andrew Bresticker wrote: > > > > > [...] > > > > > > >+static int tegra_xusb_mbox_probe(struct platform_device *pdev) > > > > > > > > > > > > >+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > >+ if (!res) > > > > > > >+ return -ENODEV; > > > > > > > > > > > > Should devm_request_mem_region() be called here to claim the region? > > > > > > > > > > > > >+ mbox->regs = devm_ioremap_nocache(&pdev->dev, res->start, > > > > > > >+ resource_size(res)); > > > > > > >+ if (!mbox->regs) > > > > > > >+ return -ENOMEM; > > > > > > > > > > > > Is _nocache required? I don't see other drivers using it. I assume there's > > > > > > nothing special about the mbox registers. > > > > > > > > > > Most drivers should be using devm_ioremap_resource() which will use the > > > > > _nocache variant of devm_ioremap() when appropriate. Usually the region > > > > > will not be marked cacheable (IORESOURCE_CACHEABLE) and therefore be > > > > > remapped uncached. > > > > > > > > > > > > > Note that ioremap() and ioremap_nocache() are the same. We really shouldn't > > > > ever call ioremap_nocache(). > > > > > > Perhaps we should remove ioremap_nocache() in that case. Or ioremap(), > > > really, and keep only those variants that do what they claim to do. > > > > That would be good, but there are many instances of either one: > > > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap | wc > > 2156 13402 183732 > > arnd@wuerfel:/git/arm-soc$ git grep -w ioremap_nocache | wc > > 485 2529 42955 > > Ugh... nothing that I currently have time for. Perhaps this is a good > one for the Janitors? I'm not sure if the kernelnewbies.org TODO list is > still frequented since many pages seem to be very old. Is there some > other place where I could add this? I'm not sure if it's really worth it. One thing we might do is just remove all definitions of ioremap_nocache and add a wrapper to include/linux/io.h, to make it more obvious what is going on. > > > > devm_ioremap_resource() and pci_iomap() checking for IORESOURCE_CACHEABLE is > > > > rather silly, since it doesn't call ioremap_cache() in that case. > > > > > > Then that should be fixed. > > > > Yes. I'd suggest we just ignore that flag and always call ioremap here. > > > > When I checked this before, IORESOURCE_CACHEABLE only ever gets set for > > PCI ROM BARs, which we don't map into the kernel. > > There's still a few users of ioremap_cache() around and they are > potential candidates for a conversion to devm_ioremap_resource(), so I > think it'd still make sense to keep the check. Possibly. Note that these are all in architecture-specific code, as evidenced by the fact that we have multiple names for this function: ioremap_cache: arm, arm64, x86, ia64, sh ioremap_cached: metag, unicore32 ioremap_cachable: mips All other architectures have none of the above. An alternative approach would be to kill off IORESOURCE_CACHEABLE and introduce a devm_ioremap_resource_cache() helper when the first driver wants it. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
