linux-kernel - Re: [PATCH 7/9] drm/i915: Remove driver side BAR release before resize

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Message-ID: <20251110225347.GA2141838@bhelgaas>
Date: Mon, 10 Nov 2025 16:53:47 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>
Cc: Alex Bennée <alex.bennee@...aro.org>,
	Simon Richter <Simon.Richter@...yros.de>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Alex Deucher <alexander.deucher@....com>,
	amd-gfx@...ts.freedesktop.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	David Airlie <airlied@...il.com>, dri-devel@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
	linux-pci@...r.kernel.org, Simona Vetter <simona@...ll.ch>,
	Christian König <christian.koenig@....com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Michał Winiarski <michal.winiarski@...el.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/9] drm/i915: Remove driver side BAR release before
 resize

i915 folks, any objection to this?

On Tue, Oct 28, 2025 at 07:35:49PM +0200, Ilpo Järvinen wrote:
> PCI core handles releasing device's resources and their rollback in
> case of failure of a BAR resizing operation. Releasing resource prior
> to calling pci_resize_resource() prevents PCI core from restoring the
> BARs as they were.
> 
> Remove driver-side release of BARs from the i915 driver.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_region_lmem.c | 12 ------------
>  1 file changed, 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> index 51bb27e10a4f..ca3de61451a3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> +++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> @@ -18,16 +18,6 @@
>  #include "gt/intel_gt_regs.h"
>  
>  #ifdef CONFIG_64BIT
> -static void _release_bars(struct pci_dev *pdev)
> -{
> -	int resno;
> -
> -	for (resno = PCI_STD_RESOURCES; resno < PCI_STD_RESOURCE_END; resno++) {
> -		if (pci_resource_len(pdev, resno))
> -			pci_release_resource(pdev, resno);
> -	}
> -}
> -
>  static void
>  _resize_bar(struct drm_i915_private *i915, int resno, resource_size_t size)
>  {
> @@ -35,8 +25,6 @@ _resize_bar(struct drm_i915_private *i915, int resno, resource_size_t size)
>  	int bar_size = pci_rebar_bytes_to_size(size);
>  	int ret;
>  
> -	_release_bars(pdev);
> -
>  	ret = pci_resize_resource(pdev, resno, bar_size);
>  	if (ret) {
>  		drm_info(&i915->drm, "Failed to resize BAR%d to %dM (%pe)\n",
> -- 
> 2.39.5
>