of_reserved_mem_device_init_by_idx() returns -EINVAL if "memory-region" is missing

of_reserved_mem_device_init_by_idx() returns -EINVAL if "memory-region" is missing

[Alexey Brodkin]

Hi Marek,

We used to use of_reserved_mem_device_init() in such a context in GPU drivers:
-------------------->8-------------------
	/* Get the optional framebuffer memory resource */
	ret = of_reserved_mem_device_init(drm->dev);
	if (ret && ret != -ENODEV)
		return ret;
-------------------->8-------------------

The point is we may have a dedicated reserved memory area or may not have (depends on a particular .dts).
Our expectation is if reserved memory area is missing then of_reserved_mem_device_init()
just returns -ENODEV and it used to work like this.

Now with your commit 59ce4039727e "of: reserved_mem: add support for using more than one region for given device"
behavior is different. of_reserved_mem_device_init_by_idx() has this:
-------------------->8-------------------
	target = of_parse_phandle(np, "memory-region", idx);
	if (!target)
		return -EINVAL;
-------------------->8-------------------

So I'm wondering which part should be fixed:
 1) of_reserved_mem itself or
 2) users of of_reserved_mem_device_init()

Any thoughts?

Regards,
Alexey
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Re: of_reserved_mem_device_init_by_idx() returns -EINVAL if "memory-region" is missing

[Marek Szyprowski]

Hi Alexey


On 2016-06-16 18:47, Alexey Brodkin wrote:
> Hi Marek,
>
> We used to use of_reserved_mem_device_init() in such a context in GPU drivers:
> -------------------->8-------------------
> 	/* Get the optional framebuffer memory resource */
> 	ret = of_reserved_mem_device_init(drm->dev);
> 	if (ret && ret != -ENODEV)
> 		return ret;
> -------------------->8-------------------
>
> The point is we may have a dedicated reserved memory area or may not have (depends on a particular .dts).
> Our expectation is if reserved memory area is missing then of_reserved_mem_device_init()
> just returns -ENODEV and it used to work like this.
>
> Now with your commit 59ce4039727e "of: reserved_mem: add support for using more than one region for given device"
> behavior is different. of_reserved_mem_device_init_by_idx() has this:
> -------------------->8-------------------
> 	target = of_parse_phandle(np, "memory-region", idx);
> 	if (!target)
> 		return -EINVAL;
> -------------------->8-------------------
>
> So I'm wondering which part should be fixed:
>   1) of_reserved_mem itself or
>   2) users of of_reserved_mem_device_init()
>
> Any thoughts?

This was my fault. The fix is already queued to linux-next, see commit
9f5a802b1d51dc80a27d828a5f7dcc8ec4a72f03 ("[media] of: reserved_mem: restore
old behavior when no region is defined"),
http://www.spinics.net/lists/linux-media/msg100972.html

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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Re: of_reserved_mem_device_init_by_idx() returns -EINVAL if "memory-region" is missing

[Alexey Brodkin]

Hi Marek,

On Fri, 2016-06-17 at 07:28 +0200, Marek Szyprowski wrote:
> Hi Alexey
> 
> 
> On 2016-06-16 18:47, Alexey Brodkin wrote:
> > 
> > Hi Marek,
> > 
> > We used to use of_reserved_mem_device_init() in such a context in GPU drivers:
> > -------------------->8-------------------
> > 	/* Get the optional framebuffer memory resource */
> > 	ret = of_reserved_mem_device_init(drm->dev);
> > 	if (ret && ret != -ENODEV)
> > 		return ret;
> > -------------------->8-------------------
> > 
> > The point is we may have a dedicated reserved memory area or may not have (depends on a particular .dts).
> > Our expectation is if reserved memory area is missing then of_reserved_mem_device_init()
> > just returns -ENODEV and it used to work like this.
> > 
> > Now with your commit 59ce4039727e "of: reserved_mem: add support for using more than one region for given device"
> > behavior is different. of_reserved_mem_device_init_by_idx() has this:
> > -------------------->8-------------------
> > 	target = of_parse_phandle(np, "memory-region", idx);
> > 	if (!target)
> > 		return -EINVAL;
> > -------------------->8-------------------
> > 
> > So I'm wondering which part should be fixed:
> >   1) of_reserved_mem itself or
> >   2) users of of_reserved_mem_device_init()
> > 
> > Any thoughts?
> 
> This was my fault. The fix is already queued to linux-next, see commit
> 9f5a802b1d51dc80a27d828a5f7dcc8ec4a72f03 ("[media] of: reserved_mem: restore
> old behavior when no region is defined"),
> http://www.spinics.net/lists/linux-media/msg100972.html
> 

Indeed with mentioned fix GPU driver now works again!
Sorry for the noise and thank you for fixing it that fast.

Regards,
Alexey
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