[PATCH 1/2] drm/amdgpu: fix power state when port pm is unavailable

[Christian König]

Am 23.11.2016 um 02:22 schrieb Peter Wu:
> When PCIe port PM is not enabled (system BIOS is pre-2015 or the
> pcie_port_pm=off parameter is set), legacy ATPX PM should still be
> marked as supported. Otherwise the GPU can fail to power on after
> runtime suspend. This affected a Dell Inspiron 5548.
>
> Ideally the BIOS date in the PCI core is lowered to 2013 (the first year
> where hybrid graphics platforms using power resources was introduced),
> but that seems more risky at this point and would not solve the
> pcie_port_pm=off issue.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98505
> Reported-and-tested-by: Nayan Deshmukh <nayan26deshmukh at gmail.com>
> Signed-off-by: Peter Wu <peter at lekensteyn.nl>

Even when lowering the BIOS date this sounds reasonable to me in the 
case of pcie_port_pm=off.

But since I'm not very deep into power management the patch is only 
Acked-by: Christian König <christian.koenig at amd.com>.

Regards,
Christian.

> ---
> Hi,
>
> This patch is already three weeks old. One alternative idea was lowering BIOS
> date in PCI core, but as pcie_port_pm=force did not have the desired effect, I
> do not think that this would help though.
>
> I have also not contacted linux-pci or Mika about lowering the year due to the
> lack of a good reason.  Might do it later though once ACPICA bug 1333 is sorted
> out such that lowering the year actually has benefits for a Nvidia laptop (or if
> some amdgpu problem can be solved by this).
>
> Both patches should probably be Cc stable (4.8+), fixing 2f5af82eeab2 and
> b8c9fd5ad4b4 ("track whether if this is a hybrid graphics platform"). There have
> been some ifdef 0's and reverts in between, so I was not sure if adding the
> Fixes tag is appropriate.
>
> Kind regards,
> Peter
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
> index 10b5ddf..951addf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atpx_handler.c
> @@ -33,6 +33,7 @@ struct amdgpu_atpx {
>   
>   static struct amdgpu_atpx_priv {
>   	bool atpx_detected;
> +	bool bridge_pm_usable;
>   	/* handle for device - and atpx */
>   	acpi_handle dhandle;
>   	acpi_handle other_handle;
> @@ -200,7 +201,11 @@ static int amdgpu_atpx_validate(struct amdgpu_atpx *atpx)
>   	atpx->is_hybrid = false;
>   	if (valid_bits & ATPX_MS_HYBRID_GFX_SUPPORTED) {
>   		printk("ATPX Hybrid Graphics\n");
> -		atpx->functions.power_cntl = false;
> +		/*
> +		 * Disable legacy PM methods only when pcie port PM is usable,
> +		 * otherwise the device might fail to power off or power on.
> +		 */
> +		atpx->functions.power_cntl = !amdgpu_atpx_priv.bridge_pm_usable;
>   		atpx->is_hybrid = true;
>   	}
>   
> @@ -471,6 +476,7 @@ static int amdgpu_atpx_power_state(enum vga_switcheroo_client_id id,
>    */
>   static bool amdgpu_atpx_pci_probe_handle(struct pci_dev *pdev)
>   {
> +	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
>   	acpi_handle dhandle, atpx_handle;
>   	acpi_status status;
>   
> @@ -485,6 +491,7 @@ static bool amdgpu_atpx_pci_probe_handle(struct pci_dev *pdev)
>   	}
>   	amdgpu_atpx_priv.dhandle = dhandle;
>   	amdgpu_atpx_priv.atpx.handle = atpx_handle;
> +	amdgpu_atpx_priv.bridge_pm_usable = parent_pdev && parent_pdev->bridge_d3;
>   	return true;
>   }
>