From 106b4a2a78b2a2f14885604891957b84bba502db Mon Sep 17 00:00:00 2001 From: Adrian Betschart Date: Fri, 11 Sep 2026 17:13:14 +0200 Subject: drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validation amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and uses the first encoding that validates. YCbCr 4:4:4 is listed before RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the "color format" property is left at AUTO, even though RGB fits the same link. That contradicts the documented AUTO behaviour for HDMI in enum drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when the bandwidth is not available or the mode is 4:2:0-only), which the amdgpu implementation of the property also describes. It also leaves the "Broadcast RGB" property without effect on such sinks, since the quantization range it selects only applies to RGB output. Try RGB first. The mask still holds every encoding the sink supports, so a mode that cannot carry RGB falls back exactly as before. For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI sink that advertised it. Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation") Suggested-by: Adolfo Rodrigues Assisted-by: Claude Code:claude-fable-5-1 Signed-off-by: Adrian Betschart Reviewed-by: Fangzhi Zuo Tested-by: Adolfo Rodrigues Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher (cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7) --- drivers/misc/open-dice.c | 232 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 232 insertions(+) create mode 100644 drivers/misc/open-dice.c (limited to 'drivers/misc/open-dice.c') diff --git a/drivers/misc/open-dice.c b/drivers/misc/open-dice.c new file mode 100644 index 000000000..b3cf59954 --- /dev/null +++ b/drivers/misc/open-dice.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2021 - Google LLC + * Author: David Brazdil + * Author: Song Guo + * + * Driver for Open Profile for DICE. + * + * This driver takes ownership of a reserved memory region containing data + * generated by the Open Profile for DICE measured boot protocol. The memory + * contents are not interpreted by the kernel but can be mapped into a userspace + * process via a misc device. Userspace can also request a wipe of the memory. + * + * Userspace can access the data with (w/o error handling): + * + * fd = open("/dev/open-dice0", O_RDWR); + * read(fd, &size, sizeof(unsigned long)); + * data = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); + * write(fd, NULL, 0); // wipe + * close(fd); + */ + +#include +#include +#include +#include +#include +#include +#include + +#define DRIVER_NAME "open-dice" + +struct open_dice_drvdata { + struct mutex lock; + char name[16]; + phys_addr_t mem_base; + resource_size_t mem_size; + struct miscdevice misc; +}; + +static inline struct open_dice_drvdata *to_open_dice_drvdata(struct file *filp) +{ + return container_of(filp->private_data, struct open_dice_drvdata, misc); +} + +static int open_dice_wipe(struct open_dice_drvdata *drvdata) +{ + void *kaddr; + + mutex_lock(&drvdata->lock); + kaddr = devm_memremap(drvdata->misc.this_device, drvdata->mem_base, + drvdata->mem_size, MEMREMAP_WC); + if (IS_ERR(kaddr)) { + mutex_unlock(&drvdata->lock); + return PTR_ERR(kaddr); + } + + memset(kaddr, 0, drvdata->mem_size); + devm_memunmap(drvdata->misc.this_device, kaddr); + mutex_unlock(&drvdata->lock); + return 0; +} + +/* + * Copies the size of the reserved memory region to the user-provided buffer. + */ +static ssize_t open_dice_read(struct file *filp, char __user *ptr, size_t len, + loff_t *off) +{ + unsigned long val = to_open_dice_drvdata(filp)->mem_size; + + return simple_read_from_buffer(ptr, len, off, &val, sizeof(val)); +} + +/* + * Triggers a wipe of the reserved memory region. The user-provided pointer + * is never dereferenced. + */ +static ssize_t open_dice_write(struct file *filp, const char __user *ptr, + size_t len, loff_t *off) +{ + if (open_dice_wipe(to_open_dice_drvdata(filp))) + return -EIO; + + /* Consume the input buffer. */ + return len; +} + +/* + * Creates a mapping of the reserved memory region in user address space. + */ +static int open_dice_mmap_prepare(struct vm_area_desc *desc) +{ + struct file *filp = desc->file; + struct open_dice_drvdata *drvdata = to_open_dice_drvdata(filp); + + if (vma_desc_test(desc, VMA_MAYSHARE_BIT)) { + /* Do not allow userspace to modify the underlying data. */ + if (vma_desc_test(desc, VMA_WRITE_BIT)) + return -EPERM; + /* Ensure userspace cannot acquire VM_WRITE later. */ + vma_desc_clear_flags(desc, VMA_MAYWRITE_BIT); + } + + /* Create write-combine mapping so all clients observe a wipe. */ + desc->page_prot = pgprot_writecombine(desc->page_prot); + vma_desc_set_flags(desc, VMA_DONTCOPY_BIT, VMA_DONTDUMP_BIT); + mmap_action_simple_ioremap(desc, drvdata->mem_base, + drvdata->mem_size); + return 0; +} + +static const struct file_operations open_dice_fops = { + .owner = THIS_MODULE, + .read = open_dice_read, + .write = open_dice_write, + .mmap_prepare = open_dice_mmap_prepare, +}; + +static int __init open_dice_probe(struct platform_device *pdev) +{ + static unsigned int dev_idx; + struct device *dev = &pdev->dev; + struct open_dice_drvdata *drvdata; + phys_addr_t mem_base; + resource_size_t mem_size; + int ret; + + if (dev->of_node) { + struct reserved_mem *rmem = of_reserved_mem_lookup(dev->of_node); + + if (!rmem) { + dev_err(dev, "failed to lookup reserved memory\n"); + return -EINVAL; + } + mem_base = rmem->base; + mem_size = rmem->size; + } else if (is_acpi_node(dev->fwnode)) { + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + + if (!res) { + dev_err(dev, "failed to get MMIO resource\n"); + return -EINVAL; + } + mem_base = res->start; + mem_size = resource_size(res); + } else { + dev_err(dev, "device not supported (no DT or ACPI node)\n"); + return -EINVAL; + } + + if (!mem_size || (mem_size > ULONG_MAX)) { + dev_err(dev, "invalid memory region size\n"); + return -EINVAL; + } + + if (!PAGE_ALIGNED(mem_base) || !PAGE_ALIGNED(mem_size)) { + dev_err(dev, "memory region must be page-aligned\n"); + return -EINVAL; + } + + drvdata = devm_kmalloc(dev, sizeof(*drvdata), GFP_KERNEL); + if (!drvdata) + return -ENOMEM; + + *drvdata = (struct open_dice_drvdata){ + .mem_base = mem_base, + .mem_size = mem_size, + .misc = (struct miscdevice){ + .parent = dev, + .name = drvdata->name, + .minor = MISC_DYNAMIC_MINOR, + .fops = &open_dice_fops, + .mode = 0600, + }, + }; + mutex_init(&drvdata->lock); + + /* Index overflow check not needed, misc_register() will fail. */ + snprintf(drvdata->name, sizeof(drvdata->name), DRIVER_NAME"%u", dev_idx++); + + ret = misc_register(&drvdata->misc); + if (ret) { + dev_err(dev, "failed to register misc device '%s': %d\n", + drvdata->name, ret); + return ret; + } + + platform_set_drvdata(pdev, drvdata); + return 0; +} + +static void open_dice_remove(struct platform_device *pdev) +{ + struct open_dice_drvdata *drvdata = platform_get_drvdata(pdev); + + misc_deregister(&drvdata->misc); +} + +static const struct of_device_id open_dice_of_match[] = { + { .compatible = "google,open-dice" }, + { } +}; + +static struct platform_driver open_dice_driver = { + .remove = open_dice_remove, + .driver = { + .name = DRIVER_NAME, + .of_match_table = open_dice_of_match, + }, +}; + +static int __init open_dice_init(void) +{ + int ret = platform_driver_probe(&open_dice_driver, open_dice_probe); + + /* DICE regions are optional. Succeed even with zero instances. */ + return (ret == -ENODEV) ? 0 : ret; +} + +static void __exit open_dice_exit(void) +{ + platform_driver_unregister(&open_dice_driver); +} + +module_init(open_dice_init); +module_exit(open_dice_exit); + +MODULE_DESCRIPTION("Driver for Open Profile for DICE."); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("David Brazdil "); +MODULE_AUTHOR("Song Guo "); -- cgit v1.3.1