commit a5516219b102 ("of/platform: Initialise default DMA masks") sets up the coherent_dma_mask of platform devices created from the device tree, but fails to do the same for AMBA (PrimeCell) devices.
This leads to a regression in kernel v4.19-rc1 triggering the WARN_ONCE() in kernel/dma/coherent.c, dma_alloc_attrs() WARN_ON_ONCE(dev && !dev->coherent_dma_mask):
------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at ../include/linux/dma-mapping.h:522 drm_gem_cma_create+0x1dc/0x21c Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 4.19.0-rc1+ #15 Hardware name: ARM-Versatile (Device Tree Support) [<c001c558>] (unwind_backtrace) from [<c00191f8>] (show_stack+0x10/0x14) [<c00191f8>] (show_stack) from [<c00246a0>] (__warn+0xcc/0xf4) [<c00246a0>] (__warn) from [<c00247dc>] (warn_slowpath_null+0x3c/0x48) [<c00247dc>] (warn_slowpath_null) from [<c025cef0>] (drm_gem_cma_create+0x1dc/0x21c) [<c025cef0>] (drm_gem_cma_create) from [<c025d3fc>] (drm_gem_cma_dumb_create+0x44/0x98) [<c025d3fc>] (drm_gem_cma_dumb_create) from [<c025c648>] (drm_client_framebuffer_create+0x80/0x204) [<c025c648>] (drm_client_framebuffer_create) from [<c0234a20>] (drm_fb_helper_generic_probe+0x4c/0x200) [<c0234a20>] (drm_fb_helper_generic_probe) from [<c0235b14>] (__drm_fb_helper_initial_config_and_unlock+0x1cc/0x454) [<c0235b14>] (__drm_fb_helper_initial_config_and_unlock) from [<c0235ea0>] (drm_fb_helper_fbdev_setup+0x104/0x218) [<c0235ea0>] (drm_fb_helper_fbdev_setup) from [<c0236410>] (drm_fbdev_cma_init+0x7c/0xac) [<c0236410>] (drm_fbdev_cma_init) from [<c0236448>] (drm_fb_cma_fbdev_init+0x8/0x14) [<c0236448>] (drm_fb_cma_fbdev_init) from [<c0260d90>] (pl111_amba_probe+0x3c8/0x4a4) [<c0260d90>] (pl111_amba_probe) from [<c01f479c>] (amba_probe+0xd8/0x154) [<c01f479c>] (amba_probe) from [<c0267398>] (really_probe+0x200/0x2ac) [<c0267398>] (really_probe) from [<c02675a4>] (driver_probe_device+0x5c/0x168) [<c02675a4>] (driver_probe_device) from [<c0267780>] (__driver_attach+0xd0/0xd4) [<c0267780>] (__driver_attach) from [<c02656c0>] (bus_for_each_dev+0x70/0xb4) [<c02656c0>] (bus_for_each_dev) from [<c0266808>] (bus_add_driver+0x170/0x204) [<c0266808>] (bus_add_driver) from [<c0268090>] (driver_register+0x74/0x108) [<c0268090>] (driver_register) from [<c000ac20>] (do_one_initcall+0x48/0x1a0) [<c000ac20>] (do_one_initcall) from [<c0507dc0>] (kernel_init_freeable+0x104/0x1c4) [<c0507dc0>] (kernel_init_freeable) from [<c03e6ee4>] (kernel_init+0x8/0xf0) [<c03e6ee4>] (kernel_init) from [<c00090e0>] (ret_from_fork+0x14/0x34) Exception stack(0xc781ffb0 to 0xc781fff8) ffa0: 00000000 00000000 00000000 00000000 ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 ffe0: 00000000 00000000 00000000 00000000 00000013 00000000 ---[ end trace 2dc47eb796bde006 ]---
This regresses the PL111 DRM driver in drivers/gpu/drm/pl111 that uses the AMBA PrimeCell to instantiate the frame buffer device, as it cannot allocate a chunk of coherent memory anymore due to the missing mask.
Fixes: a5516219b102 ("of/platform: Initialise default DMA masks") Cc: Robin Murphy robin.murphy@arm.com Cc: Rob Herring robh@kernel.org Cc: Christoph Hellwig hch@lst.de Cc: Eric Anholt eric@anholt.net Cc: Noralf Trønnes noralf@tronnes.org Signed-off-by: Linus Walleij linus.walleij@linaro.org --- I don't know which tree Robins patch came in from, but I assume Christoph's, so can you carry this patch as well? --- drivers/of/platform.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 7ba90c290a42..7435c79ca56d 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -242,6 +242,9 @@ static struct amba_device *of_amba_device_create(struct device_node *node, goto err_clear_flag;
/* setup generic device info */ + dev->dev.coherent_dma_mask = DMA_BIT_MASK(32); + if (!dev->dev.dma_mask) + dev->dev.dma_mask = &dev->dev.coherent_dma_mask; dev->dev.of_node = of_node_get(node); dev->dev.fwnode = &node->fwnode; dev->dev.parent = parent ? : &platform_bus;