Messages in this thread | | | Date | Wed, 19 Oct 2022 22:50:17 +0200 | From | "Arnd Bergmann" <> | Subject | Re: [PATCH v4 2/4] RISC-V: Fix ioremap_cache() and ioremap_wc() for systems with Svpbmt |
| |
On Wed, Oct 19, 2022, at 18:10, Anup Patel wrote: > On Wed, Oct 19, 2022 at 7:49 PM Heiko Stuebner <heiko@sntech.de> wrote: >> >> Am Mittwoch, 19. Oktober 2022, 15:11:26 CEST schrieb Anup Patel: >> > Currently, all flavors of ioremap_xyz() function maps to the generic >> > ioremap() which means any ioremap_xyz() call will always map the >> > target memory as IO using _PAGE_IOREMAP page attributes. This breaks >> > ioremap_cache() and ioremap_wc() on systems with Svpbmt because memory >> > remapped using ioremap_cache() and ioremap_wc() will use _PAGE_IOREMAP >> > page attributes. >> > >> > To address above (just like other architectures), we implement RISC-V >> > specific ioremap_cache() and ioremap_wc() which maps memory using page >> > attributes as defined by the Svpbmt specification. >> > >> > Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support") >> > Co-developed-by: Mayuresh Chitale <mchitale@ventanamicro.com> >> > Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com> >> > Signed-off-by: Anup Patel <apatel@ventanamicro.com> >> >> Wasn't there discussion around those functions in general in v2? > > Yes, there was discussion about a few drivers using ioremap_xyz() > which is discouraged and drivers should use memremap(). > > We still need the arch specific ioremap_xyz() functions/macros > added by this patch because these are required by the generic > kernel memremap() implementation (refer, kernel/iomem.c).
There is a difference between the strongly discouraged ioremap_cache() that pretty much has no valid users, and the ioremap_wt/ioremap_wc functions that are sometimes used for mapping video framebuffer or similar.
It should be sufficient to provide a arch_memremap_wb() and no ioremap_cache() to make memremap() work correctly.
Arnd
| |