Re: [PATCH 2/4] drm/i915/display: Use intel_de_read/write_fw in colorops

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 02 Jul 2026, Maarten Lankhorst <dev@lankhorst.se> wrote:
> Using the _fw variants fixes a module load error on PTL:

The commit message should explain the why. (i.e. why this is the right
fix).


>
> <4> [363.690050] Call Trace:
> <4> [363.690052]  <TASK>
> <4> [363.690055]  dump_stack_lvl+0x91/0xf0
> <4> [363.690067]  dump_stack+0x10/0x20
> <4> [363.690074]  __might_resched+0x174/0x260
> <4> [363.690087]  rt_spin_lock+0x63/0x200
> <4> [363.690092]  ? intel_dmc_wl_get+0x3c/0x140 [xe]
> <4> [363.690470]  ? __lock_acquire+0x1195/0x2860
> <4> [363.690487]  intel_dmc_wl_get+0x3c/0x140 [xe]
> <4> [363.690842]  intel_color_plane_commit_arm+0xbc/0x140 [xe]
> <4> [363.691246]  icl_plane_update_arm+0x23f/0x280 [xe]
> <4> [363.691605]  intel_plane_update_arm+0x74/0x170 [xe]
> <4> [363.691970]  intel_crtc_planes_update_arm+0x3cb/0x4c0 [xe]
> <4> [363.692338]  intel_update_crtc+0x1c3/0x840 [xe]
> <4> [363.692742]  ? intel_pre_update_crtc+0x2ce/0x470 [xe]
> <4> [363.693125]  ? intel_enable_crtc+0x123/0x150 [xe]
> <4> [363.693508]  skl_commit_modeset_enables+0x4c4/0x720 [xe]
> <4> [363.693888]  intel_atomic_commit_tail+0xd9d/0x1b30 [xe]
> <4> [363.694274]  intel_atomic_commit+0x2e8/0x330 [xe]
> <4> [363.694621]  ? intel_atomic_commit+0x2e8/0x330 [xe]
> <4> [363.694956]  drm_atomic_commit+0xaf/0xf0
> <4> [363.694962]  ? __pfx___drm_printfn_info+0x10/0x10
> <4> [363.694978]  drm_client_modeset_commit_atomic+0x25c/0x2b0
> <4> [363.695018]  drm_client_modeset_commit_locked+0x63/0x1b0
> <4> [363.695029]  drm_client_modeset_commit+0x26/0x50
> <4> [363.695035]  __drm_fb_helper_restore_fbdev_mode_unlocked+0xdc/0x110
> <4> [363.695045]  drm_fb_helper_set_par+0x2f/0x50
> <4> [363.695052]  intel_fbdev_set_par+0x39/0x90 [xe]
> <4> [363.695365]  fbcon_init+0x283/0x680
> <4> [363.695382]  visual_init+0xf2/0x190
> <4> [363.695396]  do_bind_con_driver.isra.0+0x1f1/0x4c0
> <4> [363.695416]  do_take_over_console+0x181/0x220
> <4> [363.695422]  ? vprintk_default+0x1d/0x30
> <4> [363.695436]  do_fbcon_takeover+0x85/0x160
> <4> [363.695447]  do_fb_registered+0x24c/0x2b0
> <4> [363.695460]  fbcon_fb_registered+0x3a/0x90
> <4> [363.695469]  do_register_framebuffer+0x216/0x320
> <4> [363.695488]  register_framebuffer+0x23/0x50
> <4> [363.695494]  __drm_fb_helper_initial_config_and_unlock+0x3ea/0x670
> <4> [363.695502]  ? trace_hardirqs_on+0x1e/0xd0
> <4> [363.695526]  drm_fb_helper_initial_config+0x3f/0x50
> <4> [363.695534]  drm_fbdev_client_hotplug+0x80/0xd0
> <4> [363.695543]  drm_client_register+0x8a/0xe0
> <4> [363.695556]  drm_fbdev_client_setup+0x127/0x1f0
> <4> [363.695563]  drm_client_setup+0xa7/0xe0
> <4> [363.695569]  drm_client_setup_with_color_mode+0x24/0x40
> <4> [363.695575]  intel_fbdev_setup+0x1c6/0x510 [xe]
> <4> [363.695857]  intel_display_driver_register+0xb5/0x100 [xe]
> <4> [363.696188]  ? __pfx___drm_printfn_dbg+0x10/0x10
> <4> [363.696194]  ? intel_display_driver_register+0x2e/0x100 [xe]
> <4> [363.696515]  xe_display_register+0x29/0x40 [xe]
> <4> [363.696858]  xe_device_probe+0x51a/0x9e0 [xe]
> <4> [363.697102]  ? __drmm_add_action+0x98/0x110
> <4> [363.697108]  ? __pfx___drmm_mutex_release+0x10/0x10
> <4> [363.697116]  ? __drmm_add_action_or_reset+0x1e/0x50
> <4> [363.697130]  xe_pci_probe+0x396/0x620 [xe]
> <4> [363.697423]  local_pci_probe+0x47/0xb0
> <4> [363.697431]  pci_device_probe+0xf3/0x260
> <4> [363.697444]  really_probe+0xf1/0x3c0
> <4> [363.697451]  __driver_probe_device+0x8c/0x180
> <4> [363.697458]  driver_probe_device+0x24/0xd0
> <4> [363.697464]  __driver_attach+0x10f/0x220
> <4> [363.697468]  ? __pfx___driver_attach+0x10/0x10
> <4> [363.697472]  bus_for_each_dev+0x7f/0xe0
> <4> [363.697484]  driver_attach+0x1e/0x30
> <4> [363.697487]  bus_add_driver+0x154/0x290
> <4> [363.697498]  driver_register+0x5e/0x130
> <4> [363.697504]  __pci_register_driver+0x84/0xa0
> <4> [363.697509]  xe_register_pci_driver+0x23/0x30 [xe]
> <4> [363.697762]  xe_init+0x2c/0x110 [xe]
> <4> [363.698007]  ? __pfx_xe_init+0x10/0x10 [xe]
> <4> [363.698239]  do_one_initcall+0x60/0x3f0
> <4> [363.698250]  ? __kmalloc_cache_noprof+0x470/0x690
> <4> [363.698267]  do_init_module+0x97/0x2b0
> <4> [363.698275]  load_module+0x2d08/0x2e30
> <4> [363.698280]  ? __kernel_read+0x164/0x310
> <4> [363.698312]  ? kernel_read_file+0x2ca/0x340
> <4> [363.698328]  init_module_from_file+0x96/0xe0
> <4> [363.698330]  ? init_module_from_file+0x96/0xe0
> <4> [363.698357]  idempotent_init_module+0x11d/0x340
> <4> [363.698384]  __x64_sys_finit_module+0x73/0xe0
> <4> [363.698393]  x64_sys_call+0x1e3d/0x26a0
> <4> [363.698399]  do_syscall_64+0x93/0xab0
> <4> [363.698413]  ? ext4_llseek+0xc3/0x130
> <4> [363.698425]  ? ksys_lseek+0x55/0xd0
> <4> [363.698438]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698444]  ? switch_fpu_return+0xea/0x150
> <4> [363.698454]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698465]  ? kernfs_fop_read_iter+0x197/0x210
> <4> [363.698470]  ? rw_verify_area+0x16f/0x200
> <4> [363.698482]  ? vfs_read+0x22a/0x360
> <4> [363.698498]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698506]  ? ksys_read+0x72/0xf0
> <4> [363.698520]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698526]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698532]  ? do_syscall_64+0x1b7/0xab0
> <4> [363.698535]  ? exc_page_fault+0xbd/0x2c0
> <4> [363.698545]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
> <4> [363.698549] RIP: 0033:0x715af255025d
>
> And a similar backtrace in hsw_color_commit_arm().
>
> Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
> Reviewed-by: Uma Shankar <uma.shankar@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_color.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
> index 87ced9f6ff408..cc3cdb90d6975 100644
> --- a/drivers/gpu/drm/i915/display/intel_color.c
> +++ b/drivers/gpu/drm/i915/display/intel_color.c
> @@ -1050,7 +1050,7 @@ static void hsw_color_commit_arm(struct intel_dsb *dsb,
>  	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>  	struct intel_display *display = to_intel_display(crtc);
>  
> -	intel_de_write(display, GAMMA_MODE(crtc->pipe),
> +	intel_de_write_fw(display, GAMMA_MODE(crtc->pipe),
>  		       crtc_state->gamma_mode);
>  
>  	intel_de_write_fw(display, PIPE_CSC_MODE(crtc->pipe),
> @@ -4066,7 +4066,7 @@ static void glk_load_lut_3d(struct intel_dsb *dsb,
>  	int i, lut_size = drm_color_lut32_size(blob);
>  	enum pipe pipe = crtc->pipe;
>  
> -	if (!dsb && intel_de_read(display, LUT_3D_CTL(pipe)) & LUT_3D_READY) {
> +	if (!dsb && intel_de_read_fw(display, LUT_3D_CTL(pipe)) & LUT_3D_READY) {
>  		drm_err(display->drm, "[CRTC:%d:%s] 3D LUT not ready, not loading LUTs\n",
>  			crtc->base.base.id, crtc->base.name);
>  		return;
> @@ -4084,7 +4084,7 @@ static void glk_lut_3d_commit(struct intel_dsb *dsb, struct intel_crtc *crtc, bo
>  	enum pipe pipe = crtc->pipe;
>  	u32 val = 0;
>  
> -	if (!dsb && intel_de_read(display, LUT_3D_CTL(pipe)) & LUT_3D_READY) {
> +	if (!dsb && intel_de_read_fw(display, LUT_3D_CTL(pipe)) & LUT_3D_READY) {
>  		drm_err(display->drm, "[CRTC:%d:%s] 3D LUT not ready, not committing change\n",
>  			crtc->base.base.id, crtc->base.name);
>  		return;

-- 
Jani Nikula, Intel