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

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Message-ID: <14954d6d-67bc-49f4-b394-3da4e1f80af1@bosc.ac.cn>
Date: Tue, 25 Nov 2025 18:20:00 +0800
From: ZhangZhiJie <zhangzhijie@...c.ac.cn>
To: Jani Nikula <jani.nikula@...ux.intel.com>, jeff@...fgeerling.com,
 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
Subject: Re: [PATCH v2] i915: Support Intel GPU porting on any non-x86 system.



On 2025/11/25 18:13, Jani Nikula wrote:
> On Tue, 25 Nov 2025, ZhangZhiJie <zhangzhijie@...c.ac.cn> wrote:
>> On 2025/11/24 20:24, Jani Nikula wrote:
>>> On Mon, 24 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.
>>>
>>> Seems to me it inb/outb depend on CONFIG_HAS_IOPORT. Which arch are you
>>> talking about specifically?
>>
>> riscv , has CONFIG_HAS_IOPORT.  is using for serial, GPIO., etc.
> 
> What is the actual failure mode you see?
> 
> Does it build?
> 
> BR,
> Jani.
> 
Yes, i compiled Xe driver, and it's occured load access fault when not 
disable  VGA_SEQ_*.

can found this link 
https://github.com/geerlingguy/raspberry-pi-pcie-devices/issues/510#issuecomment-3383284831

Thanks.
BR.
ZhiJie
> 
> 
>>
>> Thanks.
>> BR.
>> ZhiJie
>>>
>>>> Signed-off-by: zhangzhijie <zhangzhijie@...c.ac.cn>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_vga.c | 27 ++++++++++++++++++------
>>>>    1 file changed, 20 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c
>>>> index 6e125564db34..d5d6c4ba6434 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)
>>>>    {
>>>> @@ -66,11 +75,13 @@ void intel_vga_disable(struct intel_display *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);
>>>> +	if (likely(intel_arch_support_vga_pm(display))) {
>>>
>>> As a rule of thumb, please do not use likely/unlikely, at all.
>>>
>>> Here, intel_arch_support_vga_pm() is evaluated at build time, and the
>>> likely has no functional value, only dubious documentation value.
>>>
>>>> +		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);
>>>
>>> Both or neither get/put need to be inside the branch. Now you only get,
>>> never put, on non-x86.
>>>
>>> BR,
>>> Jani.
>>>
>>>> +		udelay(300);
>>>> +	}
>>>>    
>>>>    	intel_de_write(display, vga_reg, VGA_DISP_DISABLE);
>>>>    	intel_de_posting_read(display, vga_reg);
>>>> @@ -91,8 +102,10 @@ void intel_vga_reset_io_mem(struct intel_display *display)
>>>>    	 * 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))) {
>>>> +		outb(inb(VGA_MIS_R), VGA_MIS_W);
>>>> +		vga_put(pdev, VGA_RSRC_LEGACY_IO);
>>>> +	}
>>>>    }
>>>>    
>>>>    int intel_vga_register(struct intel_display *display)
>>>
>>
>