| Message ID | 20240930132321.2785718-10-jvetter@kalrayinc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Consolidate IO memcpy functions | expand |
On Mon, 2024-09-30 at 15:23 +0200, Julian Vetter wrote: > The um arch is the only architecture that sets the config 'NO_IOMEM', > yet drivers that use IO memory can be selected. In order to make these > drivers happy we add a dummy implementation for memcpy_{from,to}io and > memset_io functions. Maybe I'm just not understanding this series, but how does this work with lib/logic_iomem.c? You're adding these inlines unconditionally, so if this included logic_io.h, you should get symbol conflicts? Also not sure these functions should/need to do anything at all, there's no IO memory on ARCH=um in case of not having logic_io.h. Maybe even BUG_ON() or something? It can't be reachable (under correct drivers) since ioremap() always returns NULL (without logic_iomem). I think Arnd also said that other architectures might want to use logic_iomem, though I don't see any now. johannes
On 10/1/24 14:53, Johannes Berg wrote: > On Mon, 2024-09-30 at 15:23 +0200, Julian Vetter wrote: >> The um arch is the only architecture that sets the config 'NO_IOMEM', >> yet drivers that use IO memory can be selected. In order to make these >> drivers happy we add a dummy implementation for memcpy_{from,to}io and >> memset_io functions. > > Maybe I'm just not understanding this series, but how does this work > with lib/logic_iomem.c? > No, I think you're understanding the series correctly. It doesn't work. I will revert this. > You're adding these inlines unconditionally, so if this included > logic_io.h, you should get symbol conflicts? > > Also not sure these functions should/need to do anything at all, there's > no IO memory on ARCH=um in case of not having logic_io.h. Maybe even > BUG_ON() or something? It can't be reachable (under correct drivers) > since ioremap() always returns NULL (without logic_iomem). > Thanks. You're right. I added this patch because there was a build robot on some mailinglist building a random config with 'ARCH=um' and with some MTD drivers that actually use memcpy_fromio or memcpy_toio. These drivers are not guarded by a 'depends on HAS_IOMEM'. I thought I could simply fix it by adding stub functions to the um arch. Because I saw there are A LOT of drivers that use IO functions without being guarded by 'depends on HAS_IOMEM'. Not sure though, how to handle this case. > I think Arnd also said that other architectures might want to use > logic_iomem, though I don't see any now. > > johannes > > > >
On Mon, 2024-10-07 at 09:49 +0200, Julian Vetter wrote: > > > > The um arch is the only architecture that sets the config 'NO_IOMEM', (you did note this, for the comment below) > No, I think you're understanding the series correctly. It doesn't work. > I will revert this. OK. > > You're adding these inlines unconditionally, so if this included > > logic_io.h, you should get symbol conflicts? > > > > Also not sure these functions should/need to do anything at all, there's > > no IO memory on ARCH=um in case of not having logic_io.h. Maybe even > > BUG_ON() or something? It can't be reachable (under correct drivers) > > since ioremap() always returns NULL (without logic_iomem). > Thanks. You're right. I added this patch because there was a build robot > on some mailinglist building a random config with 'ARCH=um' and with > some MTD drivers that actually use memcpy_fromio or memcpy_toio. These > drivers are not guarded by a 'depends on HAS_IOMEM'. I thought I could > simply fix it by adding stub functions to the um arch. Because I saw > there are A LOT of drivers that use IO functions without being guarded > by 'depends on HAS_IOMEM'. Not sure though, how to handle this case. Right, well, as you noted above ARCH=um is the only architecture that has NO_IOMEM, so I suppose drivers are just broken. But e.g. kernel/iomem.c is also only ever built if you have HAS_IOMEM, so devm_* functions related to this are not available. So I don't know. On the one hand, it feels correct to have NO_IOMEM and HAS_IOMEM, on the other hand that's a bit of a fight against windmills? What happens now though? Seems it should _already_ not build with ARCH=um and memcpy_*io() being used? No, I guess it picked up the asm- generic version? Hm. I'm almost thinking we should let such drivers not build, and then see that they add appropriate HAS_IOMEM dependencies, but ... windmills? johannes
diff --git a/arch/um/include/asm/io.h b/arch/um/include/asm/io.h index 9ea42cc746d9..f02f40609798 100644 --- a/arch/um/include/asm/io.h +++ b/arch/um/include/asm/io.h @@ -21,6 +21,23 @@ static inline void iounmap(void __iomem *addr) } #endif /* iounmap */ +static inline void memset_io(volatile void __iomem *dst, int c, size_t count) +{ + memset((void *)dst, c, count); +} + +static inline void memcpy_toio(volatile void __iomem *to, const void *from, + size_t count) +{ + memcpy((void *)to, from, count); +} + +static inline void memcpy_fromio(void *to, const volatile void __iomem *from, + size_t count) +{ + memcpy(to, (void *)from, count); +} + #include <asm-generic/io.h> #endif
The um arch is the only architecture that sets the config 'NO_IOMEM', yet drivers that use IO memory can be selected. In order to make these drivers happy we add a dummy implementation for memcpy_{from,to}io and memset_io functions. Reviewed-by: Yann Sionneau <ysionneau@kalrayinc.com> Signed-off-by: Julian Vetter <jvetter@kalrayinc.com> --- Changes for v7: - New patch --- arch/um/include/asm/io.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)