On Wed May 20 17:30:13 2026 +0530, Pratyush Yadav wrote:
> Different platforms that use this driver might have different number of
> DMA channels allocated for CSI. So only as many DMA contexts can be used
> as the number of DMA channels available. Get the number of channels
> provided via device tree and only configure that many contexts, and
> hence only that many pads.
> 
> Reviewed-by: Yemike Abhilash Chandra <[email protected]>
> Reviewed-by: Tomi Valkeinen <[email protected]>
> Signed-off-by: Pratyush Yadav <[email protected]>
> Co-developed-by: Jai Luthra <[email protected]>
> Signed-off-by: Jai Luthra <[email protected]>
> Signed-off-by: Rishikesh Donadkar <[email protected]>
> Signed-off-by: Sakari Ailus <[email protected]>

Patch committed.

Thanks,
Sakari Ailus

 .../media/platform/ti/j721e-csi2rx/j721e-csi2rx.c  | 46 ++++++++++++++++------
 1 file changed, 33 insertions(+), 13 deletions(-)

---

diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c 
b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
index e01d95eab19c..26a8eaa98b3d 100644
--- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
+++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
@@ -43,7 +43,7 @@
 #define SHIM_PSI_CFG0_DST_TAG          GENMASK(31, 16)
 
 #define TI_CSI2RX_MAX_PIX_PER_CLK      4
-#define TI_CSI2RX_NUM_CTX              1
+#define TI_CSI2RX_MAX_CTX              32
 
 /*
  * There are no hard limits on the width or height. The DMA engine can handle
@@ -56,8 +56,8 @@
 
 #define TI_CSI2RX_PAD_SINK             0
 #define TI_CSI2RX_PAD_FIRST_SOURCE     1
-#define TI_CSI2RX_NUM_SOURCE_PADS      1
-#define TI_CSI2RX_NUM_PADS             (1 + TI_CSI2RX_NUM_SOURCE_PADS)
+#define TI_CSI2RX_MAX_SOURCE_PADS      TI_CSI2RX_MAX_CTX
+#define TI_CSI2RX_MAX_PADS             (1 + TI_CSI2RX_MAX_SOURCE_PADS)
 
 #define DRAIN_TIMEOUT_MS               50
 #define DRAIN_BUFFER_SIZE              SZ_32K
@@ -116,14 +116,15 @@ struct ti_csi2rx_dev {
        struct device                   *dev;
        void __iomem                    *shim;
        unsigned int                    enable_count;
+       unsigned int                    num_ctx;
        struct v4l2_device              v4l2_dev;
        struct media_device             mdev;
        struct media_pipeline           pipe;
-       struct media_pad                pads[TI_CSI2RX_NUM_PADS];
+       struct media_pad                pads[TI_CSI2RX_MAX_PADS];
        struct v4l2_async_notifier      notifier;
        struct v4l2_subdev              *source;
        struct v4l2_subdev              subdev;
-       struct ti_csi2rx_ctx            ctx[TI_CSI2RX_NUM_CTX];
+       struct ti_csi2rx_ctx            ctx[TI_CSI2RX_MAX_CTX];
        u8                              pix_per_clk;
        /* Buffer to drain stale data from PSI-L endpoint */
        struct {
@@ -458,7 +459,7 @@ static int csi_async_notifier_complete(struct 
v4l2_async_notifier *notifier)
                return ret;
 
        /* Create and link video nodes for all DMA contexts */
-       for (i = 0; i < TI_CSI2RX_NUM_CTX; i++) {
+       for (i = 0; i < csi->num_ctx; i++) {
                struct ti_csi2rx_ctx *ctx = &csi->ctx[i];
                struct video_device *vdev = &ctx->vdev;
 
@@ -1251,10 +1252,11 @@ static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev 
*csi)
        csi->pads[TI_CSI2RX_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
 
        for (unsigned int i = TI_CSI2RX_PAD_FIRST_SOURCE;
-            i < TI_CSI2RX_NUM_PADS; i++)
+            i < TI_CSI2RX_PAD_FIRST_SOURCE + csi->num_ctx; i++)
                csi->pads[i].flags = MEDIA_PAD_FL_SOURCE;
 
-       ret = media_entity_pads_init(&sd->entity, ARRAY_SIZE(csi->pads),
+       ret = media_entity_pads_init(&sd->entity,
+                                    TI_CSI2RX_PAD_FIRST_SOURCE + csi->num_ctx,
                                     csi->pads);
        if (ret)
                goto unregister_media;
@@ -1345,8 +1347,9 @@ cleanup_dma:
 
 static int ti_csi2rx_probe(struct platform_device *pdev)
 {
+       struct device_node *np = pdev->dev.of_node;
        struct ti_csi2rx_dev *csi;
-       int ret, i;
+       int ret = 0, i, count;
 
        csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
        if (!csi)
@@ -1368,11 +1371,28 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
        if (!csi->drain.vaddr)
                return -ENOMEM;
 
+       /* Only use as many contexts as the number of DMA channels allocated. */
+       count = of_property_count_strings(np, "dma-names");
+       if (count < 0) {
+               dev_err(csi->dev, "Failed to get DMA channel count: %d\n", 
count);
+               ret = count;
+               goto err_dma_chan;
+       }
+
+       csi->num_ctx = count;
+       if (csi->num_ctx > TI_CSI2RX_MAX_CTX) {
+               dev_err(csi->dev,
+                       "%u DMA channels passed. Maximum is %u.\n",
+                       csi->num_ctx, TI_CSI2RX_MAX_CTX);
+               ret = -EINVAL;
+               goto err_dma_chan;
+       }
+
        ret = ti_csi2rx_v4l2_init(csi);
        if (ret)
-               goto err_v4l2;
+               goto err_dma_chan;
 
-       for (i = 0; i < TI_CSI2RX_NUM_CTX; i++) {
+       for (i = 0; i < csi->num_ctx; i++) {
                csi->ctx[i].idx = i;
                csi->ctx[i].csi = csi;
                ret = ti_csi2rx_init_ctx(&csi->ctx[i]);
@@ -1399,7 +1419,7 @@ err_ctx:
        for (; i >= 0; i--)
                ti_csi2rx_cleanup_ctx(&csi->ctx[i]);
        ti_csi2rx_cleanup_v4l2(csi);
-err_v4l2:
+err_dma_chan:
        dma_free_coherent(csi->dev, csi->drain.len, csi->drain.vaddr,
                          csi->drain.paddr);
        return ret;
@@ -1410,7 +1430,7 @@ static void ti_csi2rx_remove(struct platform_device *pdev)
        struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
        unsigned int i;
 
-       for (i = 0; i < TI_CSI2RX_NUM_CTX; i++)
+       for (i = 0; i < csi->num_ctx; i++)
                ti_csi2rx_cleanup_ctx(&csi->ctx[i]);
 
        ti_csi2rx_cleanup_notifier(csi);
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