On Mon, 2021-03-08 at 18:02 +0000, Limonciello, Mario wrote: > > > > -----Original Message----- > > From: Rajneesh Bhardwaj <irenic.rajne...@gmail.com> > > Sent: Monday, March 8, 2021 11:32 > > To: Limonciello, Mario > > Cc: David E. Box; hdego...@redhat.com; mgr...@linux.intel.com; > > sasha.nef...@intel.com; platform-driver-...@vger.kernel.org; linux- > > ker...@vger.kernel.org; intel-wired-...@lists.osuosl.org > > Subject: Re: [PATCH] platform/x86: intel_pmc: Ignore GBE LTR on > > Tiger Lake > > platforms > > > > > > [EXTERNAL EMAIL] > > > > On Mon, Mar 8, 2021 at 12:20 PM Limonciello, Mario > > <mario.limoncie...@dell.com> wrote: > > > > > > > > > > > [EXTERNAL EMAIL] > > > > > > > > Due to a HW limitation, the Latency Tolerance Reporting (LTR) > > > > value > > > > programmed in the Tiger Lake GBE controller is not large enough > > > > to allow > > > > the platform to enter Package C10, which in turn prevents the > > > > platform > > from > > > > achieving its low power target during suspend-to-idle. Ignore > > > > the GBE LTR > > > > value on Tiger Lake. LTR ignore functionality is currently > > > > performed > > solely > > > > by a debugfs write call. Split out the LTR code into its own > > > > function that > > > > can be called by both the debugfs writer and by this work > > > > around. > > > > > > > > Signed-off-by: David E. Box <david.e....@linux.intel.com> > > > > Reviewed-by: Sasha Neftin <sasha.nef...@intel.com> > > > > Cc: intel-wired-...@lists.osuosl.org > > > > --- > > > > drivers/platform/x86/intel_pmc_core.c | 55 > > > > ++++++++++++++++++++------- > > > > 1 file changed, 42 insertions(+), 13 deletions(-) > > > > > > I feel like this driver change causes a weak reference between > > > e1000e and > > intel_pmc_core. > > > It would mean significantly different behavior if you use e1000e > > > but don't > > have PMC module > > > available for any reason. > > > > Can you elaborate what would change significantly? This is a FW/HW > > issue and the driver is just doing a work around to let the > > platform > > enter a deep idle state beyond PC10. If the system could enter PC10 > > and was denied entry by PMC only because of a bad LAN LTR, then > > that's > > purely an e1000e driver/GBE fw issue. > > > Because the workaround is in pmc driver, the platform behavior > becomes tied > to whether this driver was enabled. Before this the driver was > mostly for debugging > purpose and really not necessary. Now it has a functional purpose. > > As such I think it should be made apparent that you need it now for > some systems.
Agreed. This is not the first fix either. The driver needs to be built for all platforms we add support for. I'll change the Kconfig. David > > > > > > > In this case does it maybe make sense to at least use "imply" in > > > the Kconfig > > for e1000e so > > > that selecting e1000e gets intel-pmc-core enabled too? > > > > This change would tell PMC to ignore GBE LTR, regardless of which > > GBE > > driver is selected. This doesn't bind e1000e. > > Yeah, that's a good point. > > Maybe my suggestion can be to take this into documentation somewhere > instead. > > > > > > > > > > > > > > diff --git a/drivers/platform/x86/intel_pmc_core.c > > > > b/drivers/platform/x86/intel_pmc_core.c > > > > index ee2f757515b0..ab31eb646a1a 100644 > > > > --- a/drivers/platform/x86/intel_pmc_core.c > > > > +++ b/drivers/platform/x86/intel_pmc_core.c > > > > @@ -863,34 +863,45 @@ static int pmc_core_pll_show(struct > > > > seq_file *s, > > void > > > > *unused) > > > > } > > > > DEFINE_SHOW_ATTRIBUTE(pmc_core_pll); > > > > > > > > -static ssize_t pmc_core_ltr_ignore_write(struct file *file, > > > > - const char __user > > > > *userbuf, > > > > - size_t count, loff_t > > > > *ppos) > > > > +static int pmc_core_write_ltr_ignore(u32 value) > > > > { > > > > struct pmc_dev *pmcdev = &pmc; > > > > const struct pmc_reg_map *map = pmcdev->map; > > > > - u32 val, buf_size, fd; > > > > - int err; > > > > - > > > > - buf_size = count < 64 ? count : 64; > > > > - > > > > - err = kstrtou32_from_user(userbuf, buf_size, 10, &val); > > > > - if (err) > > > > - return err; > > > > + u32 fd; > > > > + int err = 0; > > > > > > > > mutex_lock(&pmcdev->lock); > > > > > > > > - if (val > map->ltr_ignore_max) { > > > > + if (fls(value) > map->ltr_ignore_max) { > > > > err = -EINVAL; > > > > goto out_unlock; > > > > } > > > > > > > > fd = pmc_core_reg_read(pmcdev, map->ltr_ignore_offset); > > > > - fd |= (1U << val); > > > > + fd |= value; > > > > pmc_core_reg_write(pmcdev, map->ltr_ignore_offset, fd); > > > > > > > > out_unlock: > > > > mutex_unlock(&pmcdev->lock); > > > > + > > > > + return err; > > > > +} > > > > + > > > > +static ssize_t pmc_core_ltr_ignore_write(struct file *file, > > > > + const char __user > > > > *userbuf, > > > > + size_t count, loff_t > > > > *ppos) > > > > +{ > > > > + u32 buf_size, val; > > > > + int err; > > > > + > > > > + buf_size = count < 64 ? count : 64; > > > > + > > > > + err = kstrtou32_from_user(userbuf, buf_size, 10, &val); > > > > + if (err) > > > > + return err; > > > > + > > > > + err = pmc_core_write_ltr_ignore(1U << val); > > > > + > > > > return err == 0 ? count : err; > > > > } > > > > > > > > @@ -1189,6 +1200,15 @@ static int quirk_xtal_ignore(const > > > > struct > > dmi_system_id > > > > *id) > > > > return 0; > > > > } > > > > > > > > +static int quirk_ltr_ignore(u32 val) > > > > +{ > > > > + int err; > > > > + > > > > + err = pmc_core_write_ltr_ignore(val); > > > > + > > > > + return err; > > > > +} > > > > + > > > > static const struct dmi_system_id pmc_core_dmi_table[] = { > > > > { > > > > .callback = quirk_xtal_ignore, > > > > @@ -1244,6 +1264,15 @@ static int pmc_core_probe(struct > > > > platform_device > > *pdev) > > > > pmcdev->pmc_xram_read_bit = > > > > pmc_core_check_read_lock_bit(); > > > > dmi_check_system(pmc_core_dmi_table); > > > > > > > > + /* > > > > + * On TGL, due to a hardware limitation, the GBE LTR > > > > blocks PC10 > > when > > > > + * a cable is attached. Tell the PMC to ignore it. > > > > + */ > > > > + if (pmcdev->map == &tgl_reg_map) { > > > > + dev_dbg(&pdev->dev, "ignoring GBE LTR\n"); > > > > + quirk_ltr_ignore(1U << 3); > > > > + } > > > > + > > > > pmc_core_dbgfs_register(pmcdev); > > > > > > > > device_initialized = true; > > > > -- > > > > 2.25.1 > > > > > > > > > -- > > Thanks, > > Rajneesh