drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

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 <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

1 files changed, 259 insertions, 0 deletions

diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c
new file mode 100644
index 000000000..833be519e
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-mapping.c
@@ -0,0 +1,259 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DMA BUF Mapping Helpers
+ *
+ */
+#include <linux/dma-buf-mapping.h>
+#include <linux/dma-resv.h>
+#include <linux/overflow.h>
+#include <linux/align.h>
+
+#define MAX_SG_ENT_SZ ALIGN_DOWN(UINT_MAX, PAGE_SIZE)
+
+static struct scatterlist *fill_sg_entry(struct scatterlist *sgl, size_t length,
+					 dma_addr_t addr)
+{
+	size_t len;
+
+	while (length) {
+		len = min(length, MAX_SG_ENT_SZ);
+		length -= len;
+		/*
+		 * DMABUF abuses scatterlist to create a scatterlist
+		 * that does not have any CPU list, only the DMA list.
+		 * Always set the page related values to NULL to ensure
+		 * importers can't use it. The phys_addr based DMA API
+		 * does not require the CPU list for mapping or unmapping.
+		 */
+		sg_set_page(sgl, NULL, 0, 0);
+		sg_dma_address(sgl) = addr;
+		sg_dma_len(sgl) = len;
+		addr += len;
+		/* Unconditionally advance. On last segment, this becomes NULL */
+		sgl = sg_next(sgl);
+	}
+
+	return sgl;
+}
+
+static unsigned int calc_sg_nents(struct dma_iova_state *state,
+				  struct phys_vec *phys_vec, size_t nr_ranges,
+				  size_t size)
+{
+	unsigned int nents = 0;
+	size_t i;
+
+	if (!state || !dma_use_iova(state)) {
+		for (i = 0; i < nr_ranges; i++) {
+			unsigned int added = DIV_ROUND_UP(phys_vec[i].len, MAX_SG_ENT_SZ);
+
+			if (check_add_overflow(nents, added, &nents))
+				return 0;
+		}
+	} else {
+		/*
+		 * In IOVA case, there is only one SG entry which spans
+		 * for whole IOVA address space, but we need to make sure
+		 * that it fits sg->length, maybe we need more.
+		 */
+		nents = DIV_ROUND_UP(size, MAX_SG_ENT_SZ);
+	}
+
+	return nents;
+}
+
+/**
+ * struct dma_buf_dma - holds DMA mapping information
+ * @sgt:    Scatter-gather table
+ * @state:  DMA IOVA state relevant in IOMMU-based DMA
+ * @size:   Total size of DMA transfer
+ */
+struct dma_buf_dma {
+	struct sg_table sgt;
+	struct dma_iova_state *state;
+	size_t size;
+};
+
+/**
+ * dma_buf_phys_vec_to_sgt - Returns the scatterlist table of the attachment
+ * from arrays of physical vectors. This funciton is intended for MMIO memory
+ * only.
+ * @attach:	[in]	attachment whose scatterlist is to be returned
+ * @provider:	[in]	p2pdma provider
+ * @phys_vec:	[in]	array of physical vectors
+ * @nr_ranges:	[in]	number of entries in phys_vec array
+ * @size:	[in]	total size of phys_vec
+ * @dir:	[in]	direction of DMA transfer
+ *
+ * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
+ * on error. May return -EINTR if it is interrupted by a signal.
+ *
+ * On success, the DMA addresses and lengths in the returned scatterlist are
+ * PAGE_SIZE aligned.
+ *
+ * A mapping must be unmapped by using dma_buf_free_sgt().
+ *
+ * NOTE: This function is intended for exporters. If direct traffic routing is
+ * mandatory exporter should call routing pci_p2pdma_map_type() before calling
+ * this function.
+ */
+struct sg_table *dma_buf_phys_vec_to_sgt(struct dma_buf_attachment *attach,
+					 struct p2pdma_provider *provider,
+					 struct phys_vec *phys_vec,
+					 size_t nr_ranges, size_t size,
+					 enum dma_data_direction dir)
+{
+	struct dma_buf_dma *dma;
+	struct scatterlist *sgl;
+	size_t mapped_len = 0;
+	unsigned int nents;
+	dma_addr_t addr;
+	size_t i;
+	int ret;
+
+	dma_resv_assert_held(attach->dmabuf->resv);
+
+	if (WARN_ON(!attach || !attach->dmabuf || !provider))
+		/* This function is supposed to work on MMIO memory only */
+		return ERR_PTR(-EINVAL);
+
+	dma = kzalloc_obj(*dma);
+	if (!dma)
+		return ERR_PTR(-ENOMEM);
+
+	switch (pci_p2pdma_map_type(provider, attach->dev)) {
+	case PCI_P2PDMA_MAP_BUS_ADDR:
+		/*
+		 * There is no need in IOVA at all for this flow.
+		 */
+		break;
+	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
+		dma->state = kzalloc_obj(*dma->state);
+		if (!dma->state) {
+			ret = -ENOMEM;
+			goto err_free_dma;
+		}
+
+		dma_iova_try_alloc(attach->dev, dma->state, 0, size);
+		break;
+	default:
+		ret = -EINVAL;
+		goto err_free_dma;
+	}
+
+	nents = calc_sg_nents(dma->state, phys_vec, nr_ranges, size);
+
+	/* sg_alloc_table will cleanly fail and return -EINVAL if nents == 0 */
+	ret = sg_alloc_table(&dma->sgt, nents, GFP_KERNEL | __GFP_ZERO);
+	if (ret)
+		goto err_free_state;
+
+	sgl = dma->sgt.sgl;
+
+	for (i = 0; i < nr_ranges; i++) {
+		if (!dma->state) {
+			addr = pci_p2pdma_bus_addr_map(provider,
+						       phys_vec[i].paddr);
+		} else if (dma_use_iova(dma->state)) {
+			ret = dma_iova_link(attach->dev, dma->state,
+					    phys_vec[i].paddr, 0,
+					    phys_vec[i].len, dir,
+					    DMA_ATTR_MMIO);
+			if (ret)
+				goto err_unmap_dma;
+
+			mapped_len += phys_vec[i].len;
+		} else {
+			addr = dma_map_phys(attach->dev, phys_vec[i].paddr,
+					    phys_vec[i].len, dir,
+					    DMA_ATTR_MMIO);
+			ret = dma_mapping_error(attach->dev, addr);
+			if (ret)
+				goto err_unmap_dma;
+		}
+
+		if (!dma->state || !dma_use_iova(dma->state))
+			sgl = fill_sg_entry(sgl, phys_vec[i].len, addr);
+	}
+
+	if (dma->state && dma_use_iova(dma->state)) {
+		WARN_ON_ONCE(mapped_len != size);
+		ret = dma_iova_sync(attach->dev, dma->state, 0, mapped_len);
+		if (ret)
+			goto err_unmap_dma;
+
+		sgl = fill_sg_entry(sgl, mapped_len, dma->state->addr);
+	}
+
+	dma->size = size;
+
+	/*
+	 * No CPU list included — set orig_nents = 0 so others can detect
+	 * this via SG table (use nents only).
+	 */
+	dma->sgt.orig_nents = 0;
+
+
+	/*
+	 * SGL must be NULL to indicate that SGL is the last one
+	 * and we allocated correct number of entries in sg_alloc_table()
+	 */
+	WARN_ON_ONCE(sgl);
+	return &dma->sgt;
+
+err_unmap_dma:
+	if (!i || !dma->state) {
+		; /* Do nothing */
+	} else if (dma_use_iova(dma->state)) {
+		dma_iova_destroy(attach->dev, dma->state, mapped_len, dir,
+				 DMA_ATTR_MMIO);
+	} else {
+		for_each_sgtable_dma_sg(&dma->sgt, sgl, i)
+			dma_unmap_phys(attach->dev, sg_dma_address(sgl),
+				       sg_dma_len(sgl), dir, DMA_ATTR_MMIO);
+	}
+	sg_free_table(&dma->sgt);
+err_free_state:
+	kfree(dma->state);
+err_free_dma:
+	kfree(dma);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_phys_vec_to_sgt, "DMA_BUF");
+
+/**
+ * dma_buf_free_sgt- unmaps the buffer
+ * @attach:	[in]	attachment to unmap buffer from
+ * @sgt:	[in]	scatterlist info of the buffer to unmap
+ * @dir:	[in]	direction of DMA transfer
+ *
+ * This unmaps a DMA mapping for @attached obtained
+ * by dma_buf_phys_vec_to_sgt().
+ */
+void dma_buf_free_sgt(struct dma_buf_attachment *attach, struct sg_table *sgt,
+		      enum dma_data_direction dir)
+{
+	struct dma_buf_dma *dma = container_of(sgt, struct dma_buf_dma, sgt);
+	int i;
+
+	dma_resv_assert_held(attach->dmabuf->resv);
+
+	if (!dma->state) {
+		; /* Do nothing */
+	} else if (dma_use_iova(dma->state)) {
+		dma_iova_destroy(attach->dev, dma->state, dma->size, dir,
+				 DMA_ATTR_MMIO);
+	} else {
+		struct scatterlist *sgl;
+
+		for_each_sgtable_dma_sg(sgt, sgl, i)
+			dma_unmap_phys(attach->dev, sg_dma_address(sgl),
+				       sg_dma_len(sgl), dir, DMA_ATTR_MMIO);
+	}
+
+	sg_free_table(sgt);
+	kfree(dma->state);
+	kfree(dma);
+
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_free_sgt, "DMA_BUF");