dmaengine: qcom: bam_dma: Avoid writing unavailable register

Avoid writing unavailable register in BAM-Lite mode.
BAM_DESC_CNT_TRSHLD register is unavailable in BAM-Lite
mode. Its only available in BAM-NDP mode. So only write
this register for clients who is using BAM-NDP.

Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
Link: https://lore.kernel.org/r/20241220094203.3510335-1-quic_mdalam@quicinc.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index bbc3276992bb012a1b79937bdbd069fc01f75331..c14557efd577046adc74fa83fd45eb239977b5fa 100644 (file)
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -59,6 +59,9 @@ struct bam_desc_hw {
 #define DESC_FLAG_NWD BIT(12)
 #define DESC_FLAG_CMD BIT(11)
 
+#define BAM_NDP_REVISION_START 0x20
+#define BAM_NDP_REVISION_END   0x27
+
 struct bam_async_desc {
        struct virt_dma_desc vd;
 
@@ -398,6 +401,7 @@ struct bam_device {
 
        /* dma start transaction tasklet */
        struct tasklet_struct task;
+       u32 bam_revision;
 };
 
 /**
@@ -441,8 +445,10 @@ static void bam_reset(struct bam_device *bdev)
        writel_relaxed(val, bam_addr(bdev, 0, BAM_CTRL));
 
        /* set descriptor threshold, start with 4 bytes */
-       writel_relaxed(DEFAULT_CNT_THRSHLD,
-                       bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
+       if (in_range(bdev->bam_revision, BAM_NDP_REVISION_START,
+                    BAM_NDP_REVISION_END))
+               writel_relaxed(DEFAULT_CNT_THRSHLD,
+                              bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
 
        /* Enable default set of h/w workarounds, ie all except BAM_FULL_PIPE */
        writel_relaxed(BAM_CNFG_BITS_DEFAULT, bam_addr(bdev, 0, BAM_CNFG_BITS));
@@ -1000,9 +1006,10 @@ static void bam_apply_new_config(struct bam_chan *bchan,
                        maxburst = bchan->slave.src_maxburst;
                else
                        maxburst = bchan->slave.dst_maxburst;
-
-               writel_relaxed(maxburst,
-                              bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
+               if (in_range(bdev->bam_revision, BAM_NDP_REVISION_START,
+                            BAM_NDP_REVISION_END))
+                       writel_relaxed(maxburst,
+                                      bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
        }
 
        bchan->reconfigure = 0;
@@ -1192,10 +1199,11 @@ static int bam_init(struct bam_device *bdev)
        u32 val;
 
        /* read revision and configuration information */
-       if (!bdev->num_ees) {
-               val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
+       val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
+       if (!bdev->num_ees)
                bdev->num_ees = (val >> NUM_EES_SHIFT) & NUM_EES_MASK;
-       }
+
+       bdev->bam_revision = val & REVISION_MASK;
 
        /* check that configured EE is within range */
        if (bdev->ee >= bdev->num_ees)