On Thu, Dec 08, 2022 at 07:46:26PM +0100, Robert Jarzmik wrote:

Jonathan Neuschäfer [off-list ref] writes:

quoted

Without further code changes this wouldn't be sufficient, because the
pinctrl driver also touches the GPIO direction registers at offset
0x0c-0x14.

Historically, this problem was adressed by a "hack" if I remember correctly,
as the
registers do overlap (on pxa27x at least, but I think on pxa25x as well) :
- GAFR (alternate functions) and GPDR (input or output) are  "pinctrl"
- GPSR, GPCR, GPLR are "gpio" registers
- the memory map (physical) at 0x40e0 0000 is as Jonathan wrote :
 - 3 u32 GPLR (gpio)
 - 3 u32 GPDR (pinctrl)
 - 3 u32 GPSR (gpio)
 - 3 u32 GPCR (gpio)

The "hack" was that one driver was mapping the area _without_ claiming it
(this
is part from memory, I didn't check in the code today). The gpio was
probably
the claiming one, while the pinctrl was the "only using one".

As of today, I should have a look what was changed, but I'm pretty sure in
all
pxa2xx architecture there is an overlap, as for these ancient platforms the
pinctrl wasn't yet separated from the gpio IC.

The only was out so far I can see from my head would be to declare multiple
very small IO ranges :
- pinctrl pxa25x : 0x40e0 000c (12 bytes), 0x40e0 0054 (32 bytes)
- pinctrl pxa25x : 0x40e0 000c (12 bytes), 0x40e0 0054 (32 bytes),  0x40e0
010c (4 bytes)
- gpio : from 0x40e0 0000 to 0x40e0 0070 included, without the  pinctrl ones

As a general guide, in gpio-pxa.c, you have the table in [1]. Think GPDR and
GAFR as
pinctrl, and all the other ones as gpio. Ah and yes, the GAFR ones are
missing in this
table.

One last think : in a pre device-tree world, when we didn't had yet the pxa
pinctrl
driver, the gpio driver was directly playing with the GPDR registers, fun
old times.

From a quick look, I think this commit is to blame:

542c25b7a209 drivers: gpio: pxa: use devm_platform_ioremap_resource()

Someone "helpfully" making this change:

-       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-       if (!res)
-               return -EINVAL;
-       gpio_reg_base = devm_ioremap(&pdev->dev, res->start,
-                                    resource_size(res));
+
+       gpio_reg_base = devm_platform_ioremap_resource(pdev, 0);

which introduces request_mem_region() to the PXA GPIO driver, resulting
in this resource clash.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel