From: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Jeff Hugo <jeff.hugo@oss.qualcomm.com>
Cc: quic_carlv@quicinc.com, quic_thanson@quicinc.com,
mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org,
Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>,
ath11k@lists.infradead.org, jjohnson@kernel.org,
quic_bqiang@quicinc.com
Subject: Re: [PATCH] bus: mhi: host: Allocate entire MHI control config once
Date: Fri, 25 Apr 2025 09:56:05 -0700 [thread overview]
Message-ID: <ea4d081c-185b-4715-9b64-da1347dab28b@oss.qualcomm.com> (raw)
In-Reply-To: <qhoirbfx5p23542hhi3kk7ftwtptsnoxgtewddbh322d74rgb2@xbupxi3ix7sx>
On 4/24/2025 10:37 PM, Manivannan Sadhasivam wrote:
> I was confused by the fact that ath11k driver adds an offset of 0x1000000 to the
> reserved region for the iova_start:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/ath/ath11k/mhi.c?h=v6.15-rc3#n331
This predates my role as maintainer.
I was an internal reviewer, but in internal review (as well as the public v1)
the code was using dedicated 'qcom' DT entries and did not have an offset.
So I looked at the entire patch history:
https://lore.kernel.org/linux-wireless/?q=s%3A%22ath11k%3A+Use+reserved+host+DDR+addresses+from+DT+for+PCI+devices%22
The offset was added in v2.
There is nothing that describes why the offset was added, and nobody
questioned it.
>
> So this means the firmware will only map the memory from reserved + 0x1000000
> for MHI data structures. But even with current implementation, the MHI stack
> doesn't know anything about the offset, because it just relies on
> dma_alloc_coherent() API which will only honor the reserved region pointed by
> 'memory' property in the node (without the offset).
>
> So I'm not sure how the firmware makes sure that the data structures lives
> within the offset region. This is more of a question to ath11k folks.
>
> But your series is not going to make it any worse. Sorry about the confusion.
>
> - Mani
>
next prev parent reply other threads:[~2025-04-25 16:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-28 16:59 [PATCH] bus: mhi: host: Allocate entire MHI control config once Jeff Hugo
2025-04-08 7:01 ` Manivannan Sadhasivam
2025-04-08 14:56 ` Jeff Hugo
2025-04-25 5:37 ` Manivannan Sadhasivam
2025-04-25 16:10 ` Jeff Hugo
2025-04-25 16:56 ` Jeff Johnson [this message]
2025-04-28 16:04 ` Manivannan Sadhasivam
2025-04-28 1:37 ` Baochen Qiang
2025-04-28 15:09 ` Jeff Hugo
2025-04-29 1:44 ` Baochen Qiang
2025-05-12 18:33 ` Jeff Hugo
2025-04-25 5:40 ` Manivannan Sadhasivam
2025-04-25 16:11 ` Jeff Hugo
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