From 526daee7301d8ec86d8de0698d4c9ada185c5470 Mon Sep 17 00:00:00 2001 From: "French, Nicholas A" Date: Sun, 11 Mar 2018 16:27:28 -0300 Subject: [PATCH] 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 Signed-off-by: Hans Verkuil [hverkuil-cisco@xs4all.nl: fix typo, split long pr_ lines up] Signed-off-by: Mauro Carvalho Chehab --- drivers/media/pci/ivtv/Kconfig | 23 ++++++++++++++++++++--- drivers/media/pci/ivtv/ivtvfb.c | 16 ++++++++++++++-- 2 files changed, 34 insertions(+), 5 deletions(-) diff --git a/drivers/media/pci/ivtv/Kconfig b/drivers/media/pci/ivtv/Kconfig index c72cbbd2d40c..06ca4e23f9fb 100644 --- a/drivers/media/pci/ivtv/Kconfig +++ b/drivers/media/pci/ivtv/Kconfig @@ -70,8 +70,25 @@ config VIDEO_FB_IVTV This is used in the Hauppauge PVR-350 card. There is a driver homepage at . - In order to use this module, you will need to boot with PAT disabled - on x86 systems, using the nopat kernel parameter. - To compile this driver as a module, choose M here: the module will be called ivtvfb. + +config VIDEO_FB_IVTV_FORCE_PAT + bool "force cx23415 framebuffer init with x86 PAT enabled" + depends on VIDEO_FB_IVTV && X86_PAT + default n + ---help--- + With PAT enabled, the cx23415 framebuffer driver does not + utilize write-combined caching on the framebuffer memory. + For this reason, the driver will by default disable itself + when initializied on a kernel with PAT enabled (i.e. not + using the nopat kernel parameter). + + 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. + + With this setting enabled, the framebuffer will initialize on + PAT-enabled systems but the framebuffer memory will be uncached. + + If unsure, say N. 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