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drm/i915/mchbar: WARN when accessing non-MCHBAR registers via intel_mchbar_read*()

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The intel_mchbar_read*() functions should only be used for
accessing MCHBAR registers. Warn if someone tries to use
them for other registers.

I suppose we could even have a dedicated type for MCHBAR
registers. But that is true for many other special register
types as well, and so far we haven't bothered adding any
special types apart from i915_mcr_reg_t.

v2: Print the register offset (Jani)
    Mention i915_mcr_reg_t (Jani)

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260331154259.24600-5-ville.syrjala@linux.intel.com
This commit is contained in:
Ville Syrjälä 2026-03-31 18:42:51 +03:00
parent 03f8a13cc1
commit 84b0366809
1 changed files with 56 additions and 0 deletions
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56
drivers/gpu/drm/i915/display/intel_mchbar.c
View File

@ -3,14 +3,66 @@
* Copyright © 2026 Intel Corporation
*/
#include <linux/minmax.h>
#include <drm/drm_print.h>
#include "intel_display_core.h"
#include "intel_mchbar.h"
#include "intel_mchbar_regs.h"
#include "intel_uncore.h"
static bool has_mchbar_mirror(struct intel_display *display)
{
return DISPLAY_VER(display) < 14;
}
static u32 mchbar_mirror_base(struct intel_display *display)
{
if (DISPLAY_VER(display) >= 6)
return MCHBAR_MIRROR_BASE_SNB;
else
return MCHBAR_MIRROR_BASE;
}
static u32 mchbar_mirror_end(struct intel_display *display)
{
if (DISPLAY_VER(display) >= 12 && !display->platform.rocketlake)
return MCHBAR_MIRROR_END_TGL;
else if (DISPLAY_VER(display) >= 11)
return MCHBAR_MIRROR_END_ICL_RKL;
else if (DISPLAY_VER(display) >= 6)
return MCHBAR_MIRROR_END_SNB;
else
return MCHBAR_MIRROR_END;
}
static u32 mchbar_mirror_len(struct intel_display *display)
{
return mchbar_mirror_end(display) - mchbar_mirror_base(display) + 1;
}
static bool is_mchbar_reg(struct intel_display *display, i915_reg_t reg)
{
return has_mchbar_mirror(display) &&
in_range32(i915_mmio_reg_offset(reg),
mchbar_mirror_base(display),
mchbar_mirror_len(display));
}
static void assert_is_mchbar_reg(struct intel_display *display, i915_reg_t reg)
{
drm_WARN(display->drm, !is_mchbar_reg(display, reg),
"Reading non-MCHBAR register 0x%x\n",
i915_mmio_reg_offset(reg));
}
u16 intel_mchbar_read16(struct intel_display *display, i915_reg_t reg)
{
struct intel_uncore *uncore = to_intel_uncore(display->drm);
assert_is_mchbar_reg(display, reg);
return intel_uncore_read16(uncore, reg);
}
@ -18,6 +70,8 @@ u32 intel_mchbar_read(struct intel_display *display, i915_reg_t reg)
{
struct intel_uncore *uncore = to_intel_uncore(display->drm);
assert_is_mchbar_reg(display, reg);
return intel_uncore_read(uncore, reg);
}
@ -26,5 +80,7 @@ u64 intel_mchbar_read64_2x32(struct intel_display *display, i915_reg_t reg)
struct intel_uncore *uncore = to_intel_uncore(display->drm);
i915_reg_t upper_reg = _MMIO(i915_mmio_reg_offset(reg) + 4);
assert_is_mchbar_reg(display, reg);
return intel_uncore_read64_2x32(uncore, reg, upper_reg);
}