hevc_d: Put command FIFO into coherent memory

Change command FIFO alloction to be from dma coherent memory rather
than from generic kernel memory that we map and unmap.
This removes a potential issue with unmap in an IRQ tail. In general
it should also be faster as it avoids the overhead inherent in map
and unmap and most streams only create short command streams.

Signed-off-by: John Cox <jc@kynesim.co.uk>

Author: jc-kynesim

drivers/media/platform/raspberrypi/hevc_dec/hevc_d_h265.c

@@ -21,6 +21,15 @@
 #include "hevc_d_hw.h"
 #include "hevc_d_video.h"
 
+/* Maximum length of command buffer before we rate it an error */
+#define CMD_BUFFER_SIZE_MAX 0x100000
+
+/* Initial size of command FIFO in commands.
+ * The FIFO will be extended if this value is exceeded but 8192 seems to
+ * deal with all streams found in the wild.
+ */
+#define CMD_BUFFER_SIZE_INIT 8192
+
 enum hevc_slice_type {
 	HEVC_SLICE_B = 0,
 	HEVC_SLICE_P = 1,
@@ -92,6 +101,24 @@ static int gptr_realloc_new(struct hevc_d_dev * const dev,
 	return 0;
 }
 
+/* Realloc with copy */
+static int gptr_realloc_copy(struct hevc_d_dev * const dev,
+			     struct hevc_d_gptr * const gptr, size_t newsize)
+{
+	struct hevc_d_gptr gnew;
+
+	if (newsize <= gptr->size)
+		return 0;
+
+	if (gptr_alloc(dev, &gnew, newsize, gptr->attrs))
+		return -ENOMEM;
+
+	memcpy(gnew.ptr, gptr->ptr, gptr->size);
+	gptr_free(dev, gptr);
+	*gptr = gnew;
+	return 0;
+}
+
 static size_t next_size(const size_t x)
 {
 	return hevc_d_round_up_size(x + 1);
@@ -106,11 +133,6 @@ static size_t next_size(const size_t x)
 
 #define HEVC_MAX_REFS V4L2_HEVC_DPB_ENTRIES_NUM_MAX
 
-struct rpi_cmd {
-	u32 addr;
-	u32 data;
-} __packed;
-
 struct hevc_d_q_aux {
 	unsigned int refcount;
 	unsigned int q_index;
@@ -133,8 +155,9 @@ struct hevc_d_dec_env {
 	unsigned int decode_order;
 	int p1_status;		/* P1 status - what to realloc */
 
-	struct rpi_cmd *cmd_fifo;
-	unsigned int cmd_len, cmd_max;
+	struct hevc_d_gptr cmd;
+	unsigned int cmd_len;
+	unsigned int cmd_max;
 	unsigned int num_slice_msgs;
 	unsigned int pic_width_in_ctbs_y;
 	unsigned int pic_height_in_ctbs_y;
@@ -167,9 +190,6 @@ struct hevc_d_dec_env {
 	struct hevc_d_q_aux *frame_aux;
 	struct hevc_d_q_aux *col_aux;
 
-	dma_addr_t cmd_addr;
-	size_t cmd_size;
-
 	dma_addr_t pu_base_vc;
 	dma_addr_t coeff_base_vc;
 	u32 pu_stride;
@@ -234,23 +254,19 @@ static inline int clip_int(const int x, const int lo, const int hi)
 /* Phase 1 command and bit FIFOs */
 static int cmds_check_space(struct hevc_d_dec_env *const de, unsigned int n)
 {
-	struct rpi_cmd *a;
 	unsigned int newmax;
 
-	if (n > 0x100000) {
-		v4l2_err(&de->ctx->dev->v4l2_dev,
-			 "%s: n %u implausible\n", __func__, n);
-		return -ENOMEM;
-	}
-
 	if (de->cmd_len + n <= de->cmd_max)
 		return 0;
 
 	newmax = roundup_pow_of_two(de->cmd_len + n);
+	if (newmax > CMD_BUFFER_SIZE_MAX) {
+		v4l2_err(&de->ctx->dev->v4l2_dev,
+			 "%s: n %u implausible\n", __func__, newmax);
+		return -ENOMEM;
+	}
 
-	a = krealloc(de->cmd_fifo, newmax * sizeof(struct rpi_cmd),
-		     GFP_KERNEL);
-	if (!a) {
+	if (gptr_realloc_copy(de->ctx->dev, &de->cmd, newmax * sizeof(u64))) {
 		v4l2_err(&de->ctx->dev->v4l2_dev,
 			 "Failed cmd buffer realloc from %u to %u\n",
 			 de->cmd_max, newmax);
@@ -259,7 +275,6 @@ static int cmds_check_space(struct hevc_d_dec_env *const de, unsigned int n)
 	v4l2_info(&de->ctx->dev->v4l2_dev,
 		  "cmd buffer realloc from %u to %u\n", de->cmd_max, newmax);
 
-	de->cmd_fifo = a;
 	de->cmd_max = newmax;
 	return 0;
 }
@@ -268,15 +283,7 @@ static int cmds_check_space(struct hevc_d_dec_env *const de, unsigned int n)
 static void p1_apb_write(struct hevc_d_dec_env *const de, const u16 addr,
 			 const u32 data)
 {
-	if (de->cmd_len >= de->cmd_max) {
-		v4l2_err(&de->ctx->dev->v4l2_dev,
-			 "%s: Overflow @ %d\n", __func__, de->cmd_len);
-		return;
-	}
-
-	de->cmd_fifo[de->cmd_len].addr = addr;
-	de->cmd_fifo[de->cmd_len].data = data;
-
+	WRITE_ONCE(((u64 *)de->cmd.ptr)[de->cmd_len], addr | ((u64)data << 32));
 	de->cmd_len++;
 }
 
@@ -1411,24 +1418,6 @@ static int updated_ps(struct hevc_d_dec_state *const s)
 	return -ENOMEM;
 }
 
-static int write_cmd_buffer(struct hevc_d_dev *const dev,
-			    struct hevc_d_dec_env *const de,
-			    const struct hevc_d_dec_state *const s)
-{
-	const size_t cmd_size = ALIGN(de->cmd_len * sizeof(de->cmd_fifo[0]),
-				      dev->cache_align);
-
-	de->cmd_addr = dma_map_single(dev->dev, de->cmd_fifo,
-				      cmd_size, DMA_TO_DEVICE);
-	if (dma_mapping_error(dev->dev, de->cmd_addr)) {
-		v4l2_err(&dev->v4l2_dev,
-			 "Map cmd buffer (%zu): FAILED\n", cmd_size);
-		return -ENOMEM;
-	}
-	de->cmd_size = cmd_size;
-	return 0;
-}
-
 static void setup_colmv(struct hevc_d_ctx *const ctx, struct hevc_d_run *run,
 			struct hevc_d_dec_state *const s)
 {
@@ -1461,12 +1450,6 @@ static void dec_env_delete(struct hevc_d_dec_env *const de)
 	struct hevc_d_ctx * const ctx = de->ctx;
 	unsigned long lock_flags;
 
-	if (de->cmd_size) {
-		dma_unmap_single(ctx->dev->dev, de->cmd_addr, de->cmd_size,
-				 DMA_TO_DEVICE);
-		de->cmd_size = 0;
-	}
-
 	aux_q_release(ctx, &de->frame_aux);
 	aux_q_release(ctx, &de->col_aux);
 
@@ -1486,8 +1469,7 @@ static void dec_env_uninit(struct hevc_d_ctx *const ctx)
 	if (ctx->dec_pool) {
 		for (i = 0; i != HEVC_D_DEC_ENV_COUNT; ++i) {
 			struct hevc_d_dec_env *const de = ctx->dec_pool + i;
-
-			kfree(de->cmd_fifo);
+			gptr_free(ctx->dev, &de->cmd);
 		}
 
 		kfree(ctx->dec_pool);
@@ -1517,11 +1499,9 @@ static int dec_env_init(struct hevc_d_ctx *const ctx)
 
 		de->ctx = ctx;
 		de->decode_order = i;
-		de->cmd_max = 8096;
-		de->cmd_fifo = kmalloc_array(de->cmd_max,
-					     sizeof(struct rpi_cmd),
-					     GFP_KERNEL);
-		if (!de->cmd_fifo)
+		de->cmd_max = CMD_BUFFER_SIZE_INIT;
+		if (gptr_alloc(ctx->dev, &de->cmd,
+			       de->cmd_max * sizeof(u64), 0))
 			goto fail;
 	}
 
@@ -1871,9 +1851,6 @@ void hevc_d_h265_setup(struct hevc_d_ctx *ctx, struct hevc_d_run *run)
 		goto fail;
 	}
 
-	if (write_cmd_buffer(dev, de, s))
-		goto fail;
-
 	for (i = 0; i < dec->num_active_dpb_entries; ++i) {
 		struct vb2_buffer *buf = vb2_find_buffer(vq, dec->dpb[i].timestamp);
 
@@ -2205,7 +2182,7 @@ static void phase1_claimed(struct hevc_d_dev *const dev, void *v)
 	hevc_d_hw_irq_active1_irq(dev, &de->irq_ent, phase1_cb, de);
 
 	/* Start the h/w */
-	apb_write_vc_addr_final(dev, RPI_CFBASE, de->cmd_addr);
+	apb_write_vc_addr_final(dev, RPI_CFBASE, de->cmd.addr);
 
 	return;