On 1/21/2025 4:24 PM, Dmitry Baryshkov wrote:
On Tue, Jan 21, 2025 at 02:42:41PM +0530, Md Sadre Alam wrote:
This patch resolves a bug from the previous commit where the
Please check Documentation/process/submitting-patches.rst, 'This
patch...'
Ok
BAM_DESC_CNT_TRSHLD register was conditionally written based on BAM-NDP
mode. The issue was reading the BAM_REVISION register hanging if num-ees
First start with the issue description, then proceed to the changes
description.
Ok
was not zero, which occurs when the SoCs power on BAM remotely. So the
BAM_REVISION register read has been moved to inside if condition.
Imperative language, please. While we are at it, please also fix commit
subject.
Sure , will fix this in next revision.
Fixes: 57a7138d0627 ("dmaengine: qcom: bam_dma: Avoid writing unavailable register")
Reported-by: Georgi Djakov <djakov@xxxxxxxxxx>
Link: https://lore.kernel.org/lkml/9ef3daa8-cdb1-49f2-8d19-a72d6210ff3a@xxxxxxxxxx/
Signed-off-by: Md Sadre Alam <quic_mdalam@xxxxxxxxxxx>
---
Change in [v3]
* Revised commit details
Change in [v2]
* Removed unnecessary if checks.
* Relocated the BAM_REVISION register read within the if condition.
Change in [v1]
* https://lore.kernel.org/lkml/1a5fc7e9-39fe-e527-efc3-1ea990bbb53b@xxxxxxxxxxx/
* Posted initial fixup for BAM revision register read handling
drivers/dma/qcom/bam_dma.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index c14557efd577..d227b4f5b6b9 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1199,11 +1199,11 @@ static int bam_init(struct bam_device *bdev)
u32 val;
/* read revision and configuration information */
Please extend the comment, mentioning why the register is read only in
!num_ees case. BTW: how do we get revision if num_ees != 0?
This revision register we need only to differentiate b/w BAM-Lite and
BAM-NDP. if num_ees != 0 then no need read this revision register.
The SOCs which is having BAM-NDP and BAM-Lite having num_ees = 0.
- val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
- if (!bdev->num_ees)
+ if (!bdev->num_ees) {
+ val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
bdev->num_ees = (val >> NUM_EES_SHIFT) & NUM_EES_MASK;
-
- bdev->bam_revision = val & REVISION_MASK;
+ bdev->bam_revision = val & REVISION_MASK;
+ }
/* check that configured EE is within range */
if (bdev->ee >= bdev->num_ees)
--
2.34.1
