linux-kernel - Re: [PATCH v2 07/11] drm/xe/vram: Use PCI rebar helpers in resize_vram

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Message-ID: <aMhz7i00wHJ6zmxa@intel.com>
Date: Mon, 15 Sep 2025 16:15:42 -0400
From: Rodrigo Vivi <rodrigo.vivi@...el.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: <linux-pci@...r.kernel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Krzysztof Wilczyński <kw@...ux.com>, Christian
 König <christian.koenig@....com>, "Michał
 Winiarski" <michal.winiarski@...el.com>, Alex Deucher
	<alexander.deucher@....com>, <amd-gfx@...ts.freedesktop.org>, David Airlie
	<airlied@...il.com>, <dri-devel@...ts.freedesktop.org>,
	<intel-gfx@...ts.freedesktop.org>, <intel-xe@...ts.freedesktop.org>, "Jani
 Nikula" <jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Lucas De Marchi
	<lucas.demarchi@...el.com>, Simona Vetter <simona@...ll.ch>, Tvrtko Ursulin
	<tursulin@...ulin.net>, ?UTF-8?q?Thomas=20Hellstr=C3=B6m?=
	<thomas.hellstrom@...ux.intel.com>, "Michael J . Ruhl" <mjruhl@...ana.ai>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v2 07/11] drm/xe/vram: Use PCI rebar helpers in
 resize_vram_bar()

On Mon, Sep 15, 2025 at 12:13:54PM +0300, Ilpo Järvinen wrote:
> PCI core provides pci_rebar_size_supported() and
> pci_rebar_size_to_bytes(), use them in resize_vram_bar() to simplify
> code.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Acked-by: Christian König <christian.koenig@....com>
> ---
>  drivers/gpu/drm/xe/xe_vram.c | 19 +++++++------------

Acked-by: Rodrigo Vivi <rodrigo.vivi@...el.com>

>  1 file changed, 7 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_vram.c b/drivers/gpu/drm/xe/xe_vram.c
> index 0b7417bb0a47..d4fbd7f74255 100644
> --- a/drivers/gpu/drm/xe/xe_vram.c
> +++ b/drivers/gpu/drm/xe/xe_vram.c
> @@ -22,8 +22,6 @@
>  #include "xe_vram.h"
>  #include "xe_vram_types.h"
>  
> -#define BAR_SIZE_SHIFT 20
> -
>  static void
>  _resize_bar(struct xe_device *xe, int resno, resource_size_t size)
>  {
> @@ -72,25 +70,22 @@ static void resize_vram_bar(struct xe_device *xe)
>  
>  	/* set to a specific size? */
>  	if (force_vram_bar_size) {
> -		u32 bar_size_bit;
> -
> -		rebar_size = force_vram_bar_size * (resource_size_t)SZ_1M;
> +		rebar_size = pci_rebar_bytes_to_size(force_vram_bar_size *
> +						     (resource_size_t)SZ_1M);
>  
> -		bar_size_bit = bar_size_mask & BIT(pci_rebar_bytes_to_size(rebar_size));
> -
> -		if (!bar_size_bit) {
> +		if (!pci_rebar_size_supported(pdev, LMEM_BAR, rebar_size)) {
>  			drm_info(&xe->drm,
>  				 "Requested size: %lluMiB is not supported by rebar sizes: 0x%x. Leaving default: %lluMiB\n",
> -				 (u64)rebar_size >> 20, bar_size_mask, (u64)current_size >> 20);
> +				 (u64)pci_rebar_size_to_bytes(rebar_size) >> 20,
> +				 bar_size_mask, (u64)current_size >> 20);
>  			return;
>  		}
>  
> -		rebar_size = 1ULL << (__fls(bar_size_bit) + BAR_SIZE_SHIFT);
> -
> +		rebar_size = pci_rebar_size_to_bytes(rebar_size);
>  		if (rebar_size == current_size)
>  			return;
>  	} else {
> -		rebar_size = 1ULL << (__fls(bar_size_mask) + BAR_SIZE_SHIFT);
> +		rebar_size = pci_rebar_size_to_bytes(__fls(bar_size_mask));
>  
>  		/* only resize if larger than current */
>  		if (rebar_size <= current_size)
> -- 
> 2.39.5
>