On Thu, 17 Mar 2022, Lucas De Marchi <[email protected]> wrote: > On Thu, Mar 17, 2022 at 08:36:17PM +0200, Jani Nikula wrote: >>Register the DMC debugfs file only on platforms that support >>DMC. There's no point in having a no-op debugfs file. > > It seems this would not change much the behavior (fail on open vs fail > on read). But the code in igt is suspicious: > > > bool igt_pm_dmc_loaded(int debugfs) > { > char buf[15]; > int len; > > len = igt_sysfs_read(debugfs, "i915_dmc_info", buf, sizeof(buf) > - 1); > if (len < 0) > return true; /* no CSR support, no DMC requirement */ > > From a quick inspection of igt_sysfs_read() it seems it would just > return 0 if there's nothing to be read. And it would return < 0 on > failure to open the file. > > These would be the affected tests: > > tests/i915/i915_pm_rpm.c: > tests/i915/i915_pm_lpsp.c: > tests/i915/i915_pm_dc.c: > igt_require(igt_pm_dmc_loaded(data.debugfs_fd));
Ok, I think I'll just drop this patch for now, don't have the time to go down that rabbit hole... Thanks, Jani. > > > Lucas De Marchi > >> >>Signed-off-by: Jani Nikula <[email protected]> >>--- >> drivers/gpu/drm/i915/display/intel_dmc.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >>diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c >>b/drivers/gpu/drm/i915/display/intel_dmc.c >>index 5de13f978e57..8dfa2aa9f8bd 100644 >>--- a/drivers/gpu/drm/i915/display/intel_dmc.c >>+++ b/drivers/gpu/drm/i915/display/intel_dmc.c >>@@ -818,9 +818,6 @@ static int intel_dmc_debugfs_status_show(struct seq_file >>*m, void *unused) >> struct intel_dmc *dmc; >> i915_reg_t dc5_reg, dc6_reg = INVALID_MMIO_REG; >> >>- if (!HAS_DMC(i915)) >>- return -ENODEV; >>- >> dmc = &i915->dmc; >> >> wakeref = intel_runtime_pm_get(&i915->runtime_pm); >>@@ -890,6 +887,9 @@ void intel_dmc_debugfs_register(struct drm_i915_private >>*i915) >> { >> struct drm_minor *minor = i915->drm.primary; >> >>+ if (!HAS_DMC(i915)) >>+ return; >>+ >> debugfs_create_file("i915_dmc_info", 0444, minor->debugfs_root, >> i915, &intel_dmc_debugfs_status_fops); >> } >>-- >>2.30.2 >> -- Jani Nikula, Intel Open Source Graphics Center
