On 19/01/18 05:55, Vinod Koul wrote:
On Tue, Jan 16, 2018 at 07:02:34PM +0000, srinivas.kandagatla@xxxxxxxxxx wrote:
From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
When Linux is master of BAM, it can directly read registers to know number
of supported channels, however when its remotely controlled reading these
registers would trigger a crash if the BAM is not yet intialized/powered up
on the remote side.
This patch adds num-channels binding to specify number of supported
dma channels on remotely controlled BAM.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
drivers/dma/qcom/bam_dma.c | 13 +++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
index 9cbf5d9df8fd..aa6822cbb230 100644
--- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
+++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
@@ -15,6 +15,8 @@ Required properties:
the secure world.
- qcom,controlled-remotely : optional, indicates that the bam is controlled by
remote proccessor i.e. execution environment.
+- num-channels : optional, indicates supported number of DMA channels in a
+ remotely controlled bam.
Example:
diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 78e488e8f96d..523bd178047a 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1083,8 +1083,10 @@ static int bam_init(struct bam_device *bdev)
if (bdev->ee >= val)
return -EINVAL;
- val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
- bdev->num_channels = val & BAM_NUM_PIPES_MASK;
+ if (!bdev->num_channels) {
+ val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
+ bdev->num_channels = val & BAM_NUM_PIPES_MASK;
+ }
if (bdev->controlled_remotely)
return 0;
@@ -1179,6 +1181,13 @@ static int bam_dma_probe(struct platform_device *pdev)
bdev->controlled_remotely = of_property_read_bool(pdev->dev.of_node,
"qcom,controlled-remotely");
+ if (bdev->controlled_remotely) {
hmm so if we remove the remotely controlled instanced from DT and then Linux
won't see them and not do anything. Do we need to do configuration of these
instances too?
No, bindings "num-channels" and "num-ees" are applicable to remote
controlled instances only, which is documented in the DT bindings.
Normally these values come from register reads, which are not possible
in case of remotely controlled instances as BAM driver would not know if
the remote is powered up or not.
thanks,
srini
+ ret = of_property_read_u32(pdev->dev.of_node, "num-channels",
+ &bdev->num_channels);
+ if (ret)
+ dev_err(bdev->dev, "num-channels unspecified in dt\n");
+ }
+
bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
if (IS_ERR(bdev->bamclk)) {
bdev->bamclk = NULL;
--
2.15.1
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