linux-kernel - Re: [PATCH v2/2] i915: Support Intel GPU porting on any non-x86 system.

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Message-ID: <98262d9d2ea7c02858aafae680a3ca0ff0a9dc9a@intel.com>
Date: Tue, 25 Nov 2025 10:38:01 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: zhangzhijie <zhangzhijie@...c.ac.cn>, jeff@...fgeerling.com,
 zhangzhijie@...c.ac.cn, wangran@...c.ac.cn, zhangjian@...c.ac.cn,
 daniel@...ll.ch, rodrigo.vivi@...el.com, joonas.lahtinen@...ux.intel.com,
 tursulin@...ulin.net, airlied@...il.com, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, guoyaxing@...c.ac.cn,
 ville.syrjala@...ux.intel.com
Subject: Re: [PATCH v2/2] i915: Support Intel GPU porting on any non-x86
 system.

On Tue, 25 Nov 2025, zhangzhijie <zhangzhijie@...c.ac.cn> wrote:
> inb/outb speccial wire not support on other ARCH.
> Should detect whether arch platform support or not.

I would rather finish the discussion on the previous version before
seeing a new version.

You mentioned risc-v in the previous thread, but it needs to be part of
the commit message too. And I still don't know what "speccial wire" is
supposed to mean here.

You still use likely/unlikely, and I told you not to.

There's no patch changelog.

The version in the subject is "v2/2", but there has already been two
"v2" posted previously.

BR,
Jani.

>
> Signed-off-by: zhangzhijie <zhangzhijie@...c.ac.cn>
> ---
>  drivers/gpu/drm/i915/display/intel_vga.c | 33 +++++++++++++++++-------
>  1 file changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c
> index 6e125564db34..d85622ba10fc 100644
> --- a/drivers/gpu/drm/i915/display/intel_vga.c
> +++ b/drivers/gpu/drm/i915/display/intel_vga.c
> @@ -41,6 +41,15 @@ static bool has_vga_pipe_sel(struct intel_display *display)
>  	return DISPLAY_VER(display) < 7;
>  }
>  
> +static bool intel_arch_support_vga_pm(struct intel_display *display)
> +{
> +#if defined(CONFIG_X86) || defined(CONFIG_X86_64)
> +	return true;
> +#else
> +	return false;
> +#endif
> +}
> +
>  /* Disable the VGA plane that we never use */
>  void intel_vga_disable(struct intel_display *display)
>  {
> @@ -64,13 +73,15 @@ void intel_vga_disable(struct intel_display *display)
>  	drm_dbg_kms(display->drm, "Disabling VGA plane on pipe %c\n",
>  		    pipe_name(pipe));
>  
> -	/* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
> -	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
> -	outb(0x01, VGA_SEQ_I);
> -	sr1 = inb(VGA_SEQ_D);
> -	outb(sr1 | VGA_SR01_SCREEN_OFF, VGA_SEQ_D);
> -	vga_put(pdev, VGA_RSRC_LEGACY_IO);
> -	udelay(300);
> +	if (likely(intel_arch_support_vga_pm(display))) {
> +		/* WaEnableVGAAccessThroughIOPort:ctg,elk,ilk,snb,ivb,vlv,hsw */
> +		vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
> +		outb(0x01, VGA_SEQ_I);
> +		sr1 = inb(VGA_SEQ_D);
> +		outb(sr1 | VGA_SR01_SCREEN_OFF, VGA_SEQ_D);
> +		vga_put(pdev, VGA_RSRC_LEGACY_IO);
> +		udelay(300);
> +	}
>  
>  	intel_de_write(display, vga_reg, VGA_DISP_DISABLE);
>  	intel_de_posting_read(display, vga_reg);
> @@ -90,9 +101,11 @@ void intel_vga_reset_io_mem(struct intel_display *display)
>  	 * sure vgacon can keep working normally without triggering interrupts
>  	 * and error messages.
>  	 */
> -	vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
> -	outb(inb(VGA_MIS_R), VGA_MIS_W);
> -	vga_put(pdev, VGA_RSRC_LEGACY_IO);
> +	if (likely(intel_arch_support_vga_pm(display))) {
> +		vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
> +		outb(inb(VGA_MIS_R), VGA_MIS_W);
> +		vga_put(pdev, VGA_RSRC_LEGACY_IO);
> +	}
>  }
>  
>  int intel_vga_register(struct intel_display *display)

-- 
Jani Nikula, Intel