diff options
| author | French, Nicholas A <naf@ou.edu> | 2018-03-11 22:27:28 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-01-21 20:33:26 +0300 |
| commit | 526daee7301d8ec86d8de0698d4c9ada185c5470 (patch) | |
| tree | 33392894fe591c647dd22ce1921e844cc6f34dfd /drivers/media/pci/ivtv/ivtvfb.c | |
| parent | dc60a4cfb77c891f67f31953025208067b05883c (diff) | |
| download | linux-526daee7301d8ec86d8de0698d4c9ada185c5470.tar.xz | |
media: ivtv: add parameter to enable ivtvfb on x86 PAT systems
ivtvfb was previously disabled for x86 PAT-enabled systems
by commit 1bf1735b4780 ("x86/mm/pat, drivers/media/ivtv:
Use arch_phys_wc_add() and require PAT disabled") as a
workaround to abstract MTRR code away from device drivers.
The driver is not easily upgradable to the PAT-aware
ioremap_wc() API since the firmware hides the address
ranges that should be marked write-combined from the driver.
However, since a write-combined cache on the framebuffer
is only a performance enhancement not a requirement for
the framebuffer to function, completely disabling the driver
in this configuration is not necessary.
Add force_pat module parameter and a corresponding kernel
configuration parameter to optionally force initialization
on PAT-enabled x86 systems with a warning about the lack of
write-combined caching, and document the reasons the driver
cannot be easily updated to support wc caching on all systems.
Signed-off-by: Nick French <naf@ou.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: fix typo, split long pr_ lines up]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'drivers/media/pci/ivtv/ivtvfb.c')
| -rw-r--r-- | drivers/media/pci/ivtv/ivtvfb.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/media/pci/ivtv/ivtvfb.c b/drivers/media/pci/ivtv/ivtvfb.c index 8ec2525d8ef5..cfd21040d0e3 100644 --- a/drivers/media/pci/ivtv/ivtvfb.c +++ b/drivers/media/pci/ivtv/ivtvfb.c @@ -55,6 +55,7 @@ /* card parameters */ static int ivtvfb_card_id = -1; static int ivtvfb_debug = 0; +static bool ivtvfb_force_pat = IS_ENABLED(CONFIG_VIDEO_FB_IVTV_FORCE_PAT); static bool osd_laced; static int osd_depth; static int osd_upper; @@ -64,6 +65,7 @@ static int osd_xres; module_param(ivtvfb_card_id, int, 0444); module_param_named(debug,ivtvfb_debug, int, 0644); +module_param_named(force_pat, ivtvfb_force_pat, bool, 0644); module_param(osd_laced, bool, 0444); module_param(osd_depth, int, 0444); module_param(osd_upper, int, 0444); @@ -79,6 +81,9 @@ MODULE_PARM_DESC(debug, "Debug level (bitmask). Default: errors only\n" "\t\t\t(debug = 3 gives full debugging)"); +MODULE_PARM_DESC(force_pat, + "Force initialization on x86 PAT-enabled systems (bool).\n"); + /* Why upper, left, xres, yres, depth, laced ? To match terminology used by fbset. Why start at 1 for left & upper coordinate ? Because X doesn't allow 0 */ @@ -1167,8 +1172,15 @@ static int ivtvfb_init_card(struct ivtv *itv) #ifdef CONFIG_X86_64 if (pat_enabled()) { - pr_warn("ivtvfb needs PAT disabled, boot with nopat kernel parameter\n"); - return -ENODEV; + if (ivtvfb_force_pat) { + pr_info("PAT is enabled. Write-combined framebuffer caching will be disabled.\n"); + pr_info("To enable caching, boot with nopat kernel parameter\n"); + } else { + pr_warn("ivtvfb needs PAT disabled for write-combined framebuffer caching.\n"); + pr_warn("Boot with nopat kernel parameter to use caching, or use the\n"); + pr_warn("force_pat module parameter to run with caching disabled\n"); + return -ENODEV; + } } #endif |