Hi

Am 11.10.22 um 22:06 schrieb Arnd Bergmann:

On Tue, Oct 11, 2022, at 1:30 PM, Thomas Zimmermann wrote:

quoted

Am 11.10.22 um 09:46 schrieb Javier Martinez Canillas:

quoted

quoted

+static bool display_get_big_endian_of(struct drm_device *dev, struct device_node *of_node)
+{
+	bool big_endian;
+
+#ifdef __BIG_ENDIAN
+	big_endian = true;
+	if (of_get_property(of_node, "little-endian", NULL))
+		big_endian = false;
+#else
+	big_endian = false;
+	if (of_get_property(of_node, "big-endian", NULL))
+		big_endian = true;
+#endif
+
+	return big_endian;
+}
+

Ah, I see. The heuristic then is whether the build is BE or LE or if the Device
Tree has an explicit node defining the endianess. The patch looks good to me:

Yes. I took this test from offb.

Has the driver been tested with little-endian kernels though? While
ppc32 kernels are always BE, you can build kernels as either big-endian
or little-endian for most (modern) powerpc64 and arm/arm64 hardware,
and I don't see why that should change the defaults of the driver
when describing the same framebuffer hardware.

Yes, I tested this on qemu's ppc64le and ppc64.

Best regards
Thomas

I could understand having a default to e.g. big-endian on all powerpc and
a default for little-endian on all arm, but having it tied to the
way the kernel is built seems wrong, and doesn't make sense in a
DT binding either.

       Arnd

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
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