media: apple: isp: Limit maximal number of buffers

ISP (FW 12.3) on t6001 times out if more buffers than count in the
buffer pool config are submitted before streaming is started.
To avoid keeping track of the number of submitted buffers limit the
number. 16 buffers / frames should be more than enough.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/media/platform/apple/isp/isp-cmd.c

@@ -395,7 +395,7 @@ int isp_cmd_ch_buffer_pool_config_set(struct apple_isp *isp, u32 chan, u16 type)
 		.opcode = CISP_OPCODE(CISP_CMD_CH_BUFFER_POOL_CONFIG_SET),
 		.chan = chan,
 		.type = type,
-		.count = 16,
+		.count = ISP_MAX_BUFFERS,
 		.meta_size0 = isp->hw->meta_size,
 		.meta_size1 = isp->hw->meta_size,
 		.unk0 = 0,

drivers/media/platform/apple/isp/isp-drv.h

@@ -23,6 +23,9 @@
 #define ISP_META_SIZE_T8103      0x4640
 #define ISP_META_SIZE_T8112      0x4840
 
+/* used to limit the user space buffers to the buffer_pool_config */
+#define ISP_MAX_BUFFERS 16
+
 enum isp_generation {
 	ISP_GEN_T8103,
 	ISP_GEN_T8112,

drivers/media/platform/apple/isp/isp-v4l2.c

@@ -11,6 +11,7 @@
 
 #include "isp-cam.h"
 #include "isp-cmd.h"
+#include "isp-drv.h"
 #include "isp-iommu.h"
 #include "isp-ipc.h"
 #include "isp-v4l2.h"
@@ -143,6 +144,13 @@ static int isp_vb2_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
 	struct apple_isp *isp = vb2_get_drv_priv(vq);
 	struct isp_format *fmt = isp_get_current_format(isp);
 
+	/* This is not strictly neccessary but makes it easy to enforce that
+	 * at most 16 buffers are submitted at once. ISP on t6001 (FW 12.3)
+	 * times out if more buffers are submitted than set in the buffer pool
+	 * config before streaming is started.
+	 */
+	*nbuffers = min_t(unsigned int, *nbuffers, ISP_MAX_BUFFERS);
+
 	if (*num_planes) {
 		if (sizes[0] < fmt->total_size)
 			return -EINVAL;