On Wed, Mar 08, 2023 at 02:36:24PM +0100, Andrzej Hajda wrote:
> Tests on DG2 machines show that releasing forcewakes during BAR resize
> results later in forcewake ack timeouts. Since forcewakes can be realeased
> asynchronously the simplest way to prevent it is to get all forcewakes
> for duration of BAR resizing.
>
> v2: hold rpm as well during resizing (Rodrigo)
oh, I really dislike this with_rpm... a get and put directly would
end up with a much clear patch... :/
but anyway:
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
> Signed-off-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> ---
> Please ignore resend of v1, my mistake.
>
> Regards
> Andrzej
> ---
> drivers/gpu/drm/i915/gt/intel_region_lmem.c | 25 +++++++++++++++------
> 1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> index 89fdfc67f8d1e0..2a3217e2890fc7 100644
> --- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> +++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> @@ -54,6 +54,7 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t
> struct resource *root_res;
> resource_size_t rebar_size;
> resource_size_t current_size;
> + intel_wakeref_t wakeref;
> u32 pci_cmd;
> int i;
>
> @@ -102,15 +103,25 @@ static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t
> return;
> }
>
> - /* First disable PCI memory decoding references */
> - pci_read_config_dword(pdev, PCI_COMMAND, &pci_cmd);
> - pci_write_config_dword(pdev, PCI_COMMAND,
> - pci_cmd & ~PCI_COMMAND_MEMORY);
> + /*
> + * Releasing forcewake during BAR resizing results in later forcewake
> + * ack timeouts and former can happen any time - it is asynchronous.
> + * Grabbing all forcewakes prevents it.
> + */
> + with_intel_runtime_pm(i915->uncore.rpm, wakeref) {
> + intel_uncore_forcewake_get(&i915->uncore, FORCEWAKE_ALL);
>
> - _resize_bar(i915, GEN12_LMEM_BAR, rebar_size);
> + /* First disable PCI memory decoding references */
> + pci_read_config_dword(pdev, PCI_COMMAND, &pci_cmd);
> + pci_write_config_dword(pdev, PCI_COMMAND,
> + pci_cmd & ~PCI_COMMAND_MEMORY);
>
> - pci_assign_unassigned_bus_resources(pdev->bus);
> - pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
> + _resize_bar(i915, GEN12_LMEM_BAR, rebar_size);
> +
> + pci_assign_unassigned_bus_resources(pdev->bus);
> + pci_write_config_dword(pdev, PCI_COMMAND, pci_cmd);
> + intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
> + }
> }
> #else
> static void i915_resize_lmem_bar(struct drm_i915_private *i915, resource_size_t lmem_size) {}
> --
> 2.34.1
>
