drm/i915/vga: Include the current pipe in the VGA disable debug message

Add some debugs to the VGA plane disable so that we can at least
see from the logs when it happens (and on which pipe). I was curious
about this at some point when I was seeing some random underruns
near the time when we disable the VGA plane, but I think in the end
that turned out to be a red herring.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250417114454.12836-5-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c
index 335e6c45deb2c39d736e4cee1edc98df46d45510..508c69b91a76f5af6688e6c1de9c26a772b31988 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vga.c
+++ b/drivers/gpu/drm/i915/display/intel_vga.c
@@ -15,6 +15,7 @@
 
 #include "i915_reg.h"
 #include "intel_de.h"
+#include "intel_display.h"
 #include "intel_vga.h"
 #include "intel_vga_regs.h"
 
@@ -28,16 +29,42 @@ static i915_reg_t intel_vga_cntrl_reg(struct intel_display *display)
                return VGACNTRL;
 }
 
+static bool has_vga_pipe_sel(struct intel_display *display)
+{
+       if (display->platform.i845g ||
+           display->platform.i865g)
+               return false;
+
+       if (display->platform.valleyview ||
+           display->platform.cherryview)
+               return true;
+
+       return DISPLAY_VER(display) < 7;
+}
+
 /* Disable the VGA plane that we never use */
 void intel_vga_disable(struct intel_display *display)
 {
        struct pci_dev *pdev = to_pci_dev(display->drm->dev);
        i915_reg_t vga_reg = intel_vga_cntrl_reg(display);
+       enum pipe pipe;
+       u32 tmp;
        u8 sr1;
 
-       if (intel_de_read(display, vga_reg) & VGA_DISP_DISABLE)
+       tmp = intel_de_read(display, vga_reg);
+       if (tmp & VGA_DISP_DISABLE)
                return;
 
+       if (display->platform.cherryview)
+               pipe = REG_FIELD_GET(VGA_PIPE_SEL_MASK_CHV, tmp);
+       else if (has_vga_pipe_sel(display))
+               pipe = REG_FIELD_GET(VGA_PIPE_SEL_MASK, tmp);
+       else
+               pipe = PIPE_A;
+
+       drm_dbg_kms(display->drm, "Disabling VGA plane on pipe %c\n",
+                   pipe_name(pipe));
+
        /* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
        vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
        outb(0x01, VGA_SEQ_I);