From: Stephan Gerhold <stephan.gerhold@linaro.org>
To: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
Cc: Stephan Gerhold <stephan@gerhold.net>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Loic Poulain <loic.poulain@oss.qualcomm.com>,
Sergey Ryazanov <ryazanov.s.a@gmail.com>,
Johannes Berg <johannes@sipsolutions.net>,
linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
chris.lew@oss.qualcomm.com,
Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Subject: Re: [PATCH 1/2] dt-bindings: net: qcom,bam-dmux: Add qcom,shikra-bam-dmux compatible
Date: Tue, 14 Jul 2026 09:11:24 +0200 [thread overview]
Message-ID: <alXhHH0mGvFeUMd7@linaro.org> (raw)
In-Reply-To: <20260714-qcom-bam-dmux-vmid-ext-v1-1-3f29da7cca76@oss.qualcomm.com>
On Tue, Jul 14, 2026 at 11:02:31AM +0530, Vishnu Santhosh wrote:
> On platforms where the modem DMAs into the BAM-DMUX RX data buffers and
> the XPU enforces per-region access control, each individually
> DMA-mapped RX buffer consumes an XPU resource group. With only ~16
> groups available, the per-buffer mappings exhaust the table and inbound
> transfers fault.
>
> Add qcom,shikra-bam-dmux as an additional compatible for the Shikra SoC,
> paired with the generic qcom,bam-dmux fallback, so the driver can match
> on it via its of_device_id table.
>
> Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
IMHO (the DT maintainers might disagree) this is not a different
BAM DMUX hardware block on Shikra, just a different firmware
configuration. I'm sure the existing SoCs also have those XPU blocks,
they just don't make use of it.
Personally, I would rather describe this with an optional "qcom,vmid"
property similar to your bam-dma patch, allowed for all SoCs.
Thanks,
Stephan
next prev parent reply other threads:[~2026-07-14 7:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-14 5:32 [PATCH 0/2] net: wwan: qcom_bam_dmux: Alloc RX buffers as a single coherent block Vishnu Santhosh
2026-07-14 5:32 ` [PATCH 1/2] dt-bindings: net: qcom,bam-dmux: Add qcom,shikra-bam-dmux compatible Vishnu Santhosh
2026-07-14 7:11 ` Stephan Gerhold [this message]
2026-07-14 14:03 ` Vishnu Santhosh
2026-07-14 5:32 ` [PATCH 2/2] net: wwan: qcom_bam_dmux: Alloc RX buffers as a single coherent block Vishnu Santhosh
2026-07-14 7:35 ` Stephan Gerhold
2026-07-14 15:47 ` Vishnu Santhosh
2026-07-14 7:55 ` Jagielski, Jedrzej
2026-07-14 16:31 ` Vishnu Santhosh
2026-07-14 7:53 ` [PATCH 0/2] " Jagielski, Jedrzej
2026-07-14 16:08 ` Vishnu Santhosh
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