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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <9ef3daa8-cdb1-49f2-8d19-a72d6210ff3a@kernel.org>
Date: Tue, 7 Jan 2025 23:30:18 +0200
From: Georgi Djakov <djakov@...nel.org>
To: Md Sadre Alam <quic_mdalam@...cinc.com>, vkoul@...nel.org,
 linux-arm-msm@...r.kernel.org, dmaengine@...r.kernel.org
Cc: quic_mmanikan@...cinc.com, quic_srichara@...cinc.com,
 quic_varada@...cinc.com, robin.murphy@....com, u.kleine-koenig@...libre.com,
 martin.petersen@...cle.com, fenghua.yu@...el.com, av2082000@...il.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] dmaengine: qcom: bam_dma: Avoid writing unavailable
 register

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@...cinc.com>
> ---

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.

[..]

>   
>   	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