Hi,
Thanks for the info.
Am 06.01.25 um 08:03 schrieb Binbin Zhou:
[...]
Could you point to the exact call that fails within simpledrm?
If we use simpledrm directly, the following error occurs:
[ 8.289823] simple-framebuffer simple-framebuffer.0: [drm] *ERROR*
could not acquire memory range [mem 0xe0031200000-0xe00315fffff flags
0x200]: -16
[ 8.312681] simple-framebuffer simple-framebuffer.0: probe with
driver simple-framebuffer failed with error -16
The reason for the failure: overlapping resources.
https://elixir.bootlin.com/linux/v6.12.6/source/drivers/video/aperture.c#L175
This error means that there's already an instance of simpledrm bound to
the BMC framebuffer. So you already have a working display and some
graphics under Linux without the new driver, right?
If so, why do you need a new driver that does exactly the same as simpledrm?
Best regards
Thomas
Because although we register the driver in platform form, its memory
belongs to pci space and we can see the corresponding pci probe and
resource allocation in Patch-1.
I don't understand. Graphics memory is often located on the PCI bus.
What is so special about this one?
Therefore, we need to use aperture_remove_conflicting_pci_devices().
So there is already a device that represents the graphics card? That's
what you'd remove here? If you only add that MFD device, who owns the
framebuffer? If it's the PCI device from patch 1 ("ls2k-bmc"), why does
aperture_remove_conflicting_pci_devices() not remove that device? I'm
somewhat confused, because the logic in your driver mostly looks like it
binds to a pre-configured framebuffer, but some of the code doesn't.
Perhaps the use of aperture_remove_conflicting_pci_devices() is wrong,
as there is only one display device for the LS2K BMC and there will be
no phase conflict.
When I tried to use that API before, it was partly due to the error
above, and partly because I referenced that other display drivers via
pci_driver.probe() would have it, just in case I used it, which was
probably the wrong choice.
The resources for pci bar0 are as follows:
BAR0: e0030000000/SZ_32M
0x0 0x600000 0xf00001c 16M 32M
+----+--------------+--------+-----------+---+-----------------+
| 2M | simpldrm | | IPMI | | video env |
+-----------------------------------------------------------------+
The mfd driver registers the ls2kbmc-framebuffer and ls2k-ipmi-si
devices according to the resource allocation shown above. At the same
time, the ls2kbmc drm is bound to the pre-configured “simpldrm”
resource in the above figure, which is passed through the
ls2kbmc-framebuffer driver. In addition, the resolution is read from
“video env” for the time being, and the resolution adaption is planned
to be added later.
Best regards Thomas
Also, since we are using BMC display, the display will be disconnected
when BMC reset, at this time we need to push the display data (crtc,
connector, etc.) manually as shown in Patch-4.
Probably it's not the most suitable way to implement it.
Best regards
Thomas
+ },
+ .probe = ls2kbmc_probe,
+ .remove = ls2kbmc_remove,
+};
+
+module_platform_driver(ls2kbmc_platform_driver);
+
+MODULE_DESCRIPTION("DRM driver for Loongson-2K BMC");
+MODULE_LICENSE("GPL");
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
--
Thanks.
Binbin
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
