NACK: [PATCH 1/1][SRU][H] platform/x86: intel_pmc_core: Ignore GBE LTR on Tiger Lake platforms

[Tim Gardner]

This looks more like a backport to me. How about some explanation for 
the missing parts of the original commit ? pmc_core_send_ltr_ignore() 
also had some changes. pmc_core_ltr_ignore_write() is new, but likely 
unused.

rtg

On 7/30/21 2:09 AM, AceLan Kao wrote:
> From: "David E. Box" <david.e.box at linux.intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1919116
> 
> 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.box at linux.intel.com>
> Reviewed-by: Sasha Neftin <sasha.neftin at intel.com>
> Cc: intel-wired-lan at lists.osuosl.org
> Reviewed-by: Rajneesh Bhardwaj <irenic.rajneesh at gmail.com>
> Link: https://lore.kernel.org/r/20210319201844.3305399-2-david.e.box@linux.intel.com
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> (cherry picked from commit d1635448f1105e549b4041aab930dbc6945fc635)
> Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>
> ---
>   drivers/platform/x86/intel_pmc_core.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
> index 260d49dca1ad..765f15edfe24 100644
> --- a/drivers/platform/x86/intel_pmc_core.c
> +++ b/drivers/platform/x86/intel_pmc_core.c
> @@ -1277,6 +1277,15 @@ static int pmc_core_probe(struct platform_device *pdev)
>   		pmc_core_send_ltr_ignore(3);
>   	}
>   
> +	/*
> +	 * 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");
> +		pmc_core_send_ltr_ignore(3);
> +	}
> +
>   	pmc_core_dbgfs_register(pmcdev);
>   
>   	device_initialized = true;
> 

-- 
-----------
Tim Gardner
Canonical, Inc