Re: [PATCH v4] dmaengine: qcom: bam_dma: Avoid writing unavailable register

[Md Sadre Alam]

On 1/8/2025 4:40 PM, Vinod Koul wrote:
> On 07-01-25, 23:30, Georgi Djakov wrote:
> > On 20.12.24 11:42, Md Sadre Alam wrote:
> > > 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@xxxxxxxxxxx>
> > > ---
> >
> > My Dragonboard db845c fails to boot on recent linux-next releases and
> > git bisect points to this patch. It boots again when it's reverted.
>
> Should we revert?
I am checking this will fix and post patch quickly.
> > [..]
> >
> > >    	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;
> >
> > The problem seems to occur when we try to read the revision for the
> > slimbus bam instance at 0x17184000 (which has "qcom,num-ees = <2>;").
> >
> > Thanks,
> > Georgi