From 3bf3710e3718a5aebdf465343bc1125b6e8cca96 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= Date: Wed, 2 Jun 2021 10:38:10 +0200 Subject: drm/ttm: Add a generic TTM memcpy move for page-based iomem MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The internal ttm_bo_util memcpy uses ioremap functionality, and while it probably might be possible to use it for copying in- and out of sglist represented io memory, using io_mem_reserve() / io_mem_free() callbacks, that would cause problems with fault(). Instead, implement a method mapping page-by-page using kmap_local() semantics. As an additional benefit we then avoid the occasional global TLB flushes of ioremap() and consuming ioremap space, elimination of a critical point of failure and with a slight change of semantics we could also push the memcpy out async for testing and async driver development purposes. A special linear iomem iterator is introduced internally to mimic the old ioremap behaviour for code-paths that can't immediately be ported over. This adds to the code size and should be considered a temporary solution. Looking at the code we have a lot of checks for iomap tagged pointers. Ideally we should extend the core memremap functions to also accept uncached memory and kmap_local functionality. Then we could strip a lot of code. Cc: Christian König Signed-off-by: Thomas Hellström Reviewed-by: Christian König Link: https://lore.kernel.org/r/20210602083818.241793-4-thomas.hellstrom@linux.intel.com --- drivers/gpu/drm/ttm/ttm_module.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'drivers/gpu/drm/ttm/ttm_module.c') diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c index 56b0efdba1a9..997c458f68a9 100644 --- a/drivers/gpu/drm/ttm/ttm_module.c +++ b/drivers/gpu/drm/ttm/ttm_module.c @@ -31,12 +31,47 @@ */ #include #include +#include #include #include #include +#include #include "ttm_module.h" +/** + * ttm_prot_from_caching - Modify the page protection according to the + * ttm cacing mode + * @caching: The ttm caching mode + * @tmp: The original page protection + * + * Return: The modified page protection + */ +pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp) +{ + /* Cached mappings need no adjustment */ + if (caching == ttm_cached) + return tmp; + +#if defined(__i386__) || defined(__x86_64__) + if (caching == ttm_write_combined) + tmp = pgprot_writecombine(tmp); + else if (boot_cpu_data.x86 > 3) + tmp = pgprot_noncached(tmp); +#endif +#if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \ + defined(__powerpc__) || defined(__mips__) + if (caching == ttm_write_combined) + tmp = pgprot_writecombine(tmp); + else + tmp = pgprot_noncached(tmp); +#endif +#if defined(__sparc__) + tmp = pgprot_noncached(tmp); +#endif + return tmp; +} + struct dentry *ttm_debugfs_root; static int __init ttm_init(void) -- cgit v1.2.3