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/firmware/google/cbmem.c | 136 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 drivers/firmware/google/cbmem.c (limited to 'drivers/firmware/google/cbmem.c') diff --git a/drivers/firmware/google/cbmem.c b/drivers/firmware/google/cbmem.c new file mode 100644 index 000000000..4d20477ed --- /dev/null +++ b/drivers/firmware/google/cbmem.c @@ -0,0 +1,136 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * cbmem.c + * + * Driver for exporting cbmem entries in sysfs. + * + * Copyright 2022 Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "coreboot_table.h" + +struct cbmem_entry { + char *mem_file_buf; + u32 size; +}; + +static struct cbmem_entry *to_cbmem_entry(struct kobject *kobj) +{ + return dev_get_drvdata(kobj_to_dev(kobj)); +} + +static ssize_t mem_read(struct file *filp, struct kobject *kobj, + const struct bin_attribute *bin_attr, char *buf, loff_t pos, + size_t count) +{ + struct cbmem_entry *entry = to_cbmem_entry(kobj); + + return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf, + entry->size); +} + +static ssize_t mem_write(struct file *filp, struct kobject *kobj, + const struct bin_attribute *bin_attr, char *buf, loff_t pos, + size_t count) +{ + struct cbmem_entry *entry = to_cbmem_entry(kobj); + + if (pos < 0 || pos >= entry->size) + return -EINVAL; + if (count > entry->size - pos) + count = entry->size - pos; + + memcpy(entry->mem_file_buf + pos, buf, count); + return count; +} +static const BIN_ATTR_ADMIN_RW(mem, 0); + +static ssize_t address_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct coreboot_device *cbdev = dev_to_coreboot_device(dev); + + return sysfs_emit(buf, "0x%llx\n", cbdev->cbmem_entry.address); +} +static DEVICE_ATTR_RO(address); + +static ssize_t size_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct coreboot_device *cbdev = dev_to_coreboot_device(dev); + + return sysfs_emit(buf, "0x%x\n", cbdev->cbmem_entry.entry_size); +} +static DEVICE_ATTR_RO(size); + +static struct attribute *attrs[] = { + &dev_attr_address.attr, + &dev_attr_size.attr, + NULL, +}; + +static const struct bin_attribute *const bin_attrs[] = { + &bin_attr_mem, + NULL, +}; + +static const struct attribute_group cbmem_entry_group = { + .attrs = attrs, + .bin_attrs = bin_attrs, +}; + +static const struct attribute_group *dev_groups[] = { + &cbmem_entry_group, + NULL, +}; + +static int cbmem_entry_probe(struct coreboot_device *dev) +{ + struct cbmem_entry *entry; + + entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + dev_set_drvdata(&dev->dev, entry); + entry->mem_file_buf = devm_memremap(&dev->dev, dev->cbmem_entry.address, + dev->cbmem_entry.entry_size, + MEMREMAP_WB); + if (IS_ERR(entry->mem_file_buf)) + return PTR_ERR(entry->mem_file_buf); + + entry->size = dev->cbmem_entry.entry_size; + + return 0; +} + +static const struct coreboot_device_id cbmem_ids[] = { + { .tag = LB_TAG_CBMEM_ENTRY }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(coreboot, cbmem_ids); + +static struct coreboot_driver cbmem_entry_driver = { + .probe = cbmem_entry_probe, + .drv = { + .name = "cbmem", + .dev_groups = dev_groups, + }, + .id_table = cbmem_ids, +}; +module_coreboot_driver(cbmem_entry_driver); + +MODULE_AUTHOR("Jack Rosenthal "); +MODULE_DESCRIPTION("Driver for exporting CBMEM entries in sysfs"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1