Re: [PATCH v3] fbdev/hga: Request memory region before ioremap

[Hardik Phalet <hardik.phalet@pm.me>]

On Tue Mar 10, 2026 at 6:38 PM IST, Thomas Zimmermann wrote:
> Hi,
>
> thanks for the patch. Let's hope there are no conflicts with other
> hardware.  IDK if anyone still uses this driver.
Hi Thomas,

Thanks for reviewing this.

Since I currently do not have access to the hardware needed to test the
change properly, I will drop this patch for now. I may revisit it once I
can validate the behavior on real hardware. 

Thanks again for your feedback.

Best regards,
Hardik
>
> Am 10.03.26 um 13:30 schrieb Hardik Phalet:
>> The driver calls ioremap() on the HGA video memory at 0xb0000 without
>> first reserving the physical address range. This leaves the kernel
>> resource tree incomplete and can cause silent conflicts with other
>> drivers claiming the same range.
>>
>> Add a devm_request_mem_region() call before ioremap() in
>> hga_card_detect() to reserve the memory region.
>>
>> Signed-off-by: Hardik Phalet <hardik.phalet@pm.me>
>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
>
> Best regards
> Thomas
>
>> ---
>> Changes in v3:
>> - Used dev_err() to log memory region request, based on another review
>>    comment by Thomas [2].
>> Changes in v2:
>> - Used devm_request_mem_region instead of request_mem_region, based on a
>> 	review comment by Thomas [1].
>>
>> v1: https://lore.kernel.org/all/20260310064124.602848-1-hardik.phalet@pm.me/
>> v2: https://lore.kernel.org/all/20260310113810.789575-1-hardik.phalet@pm.me/
>> [1]: https://lore.kernel.org/all/5f9749ba-18a8-4b6b-a6e7-a011a3871bfb@suse.de/
>> [2]: https://lore.kernel.org/all/ec635591-c861-4aa8-a259-718690ddaa4e@suse.de/
>>
>>   drivers/video/fbdev/hgafb.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/video/fbdev/hgafb.c b/drivers/video/fbdev/hgafb.c
>> index 14418aa3791a..d32fd1c5217c 100644
>> --- a/drivers/video/fbdev/hgafb.c
>> +++ b/drivers/video/fbdev/hgafb.c
>> @@ -276,7 +276,7 @@ static void hga_blank(int blank_mode)
>>   	spin_unlock_irqrestore(&hga_reg_lock, flags);
>>   }
>>
>> -static int hga_card_detect(void)
>> +static int hga_card_detect(struct platform_device *pdev)
>>   {
>>   	int count = 0;
>>   	void __iomem *p, *q;
>> @@ -284,6 +284,11 @@ static int hga_card_detect(void)
>>
>>   	hga_vram_len  = 0x08000;
>>
>> +	if (!devm_request_mem_region(&pdev->dev, 0xb0000, hga_vram_len, "hgafb")) {
>> +		dev_err(&pdev->dev, "cannot reserve video memory at 0xb0000\n");
>> +		return -EBUSY;
>> +	}
>> +
>>   	hga_vram = ioremap(0xb0000, hga_vram_len);
>>   	if (!hga_vram)
>>   		return -ENOMEM;
>> @@ -568,7 +573,7 @@ static int hgafb_probe(struct platform_device *pdev)
>>   	struct fb_info *info;
>>   	int ret;
>>
>> -	ret = hga_card_detect();
>> +	ret = hga_card_detect(pdev);
>>   	if (ret)
>>   		return ret;
>>
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
> GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)