linux-kernel - Re: [PATCH 5/5] bus: mhi: host: Remove redundant dma

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: <fa92f431-500d-df0f-85f6-55cf5017a80b@quicinc.com>
Date:   Tue, 3 May 2022 19:22:28 -0700
From:   Hemant Kumar <quic_hemantk@...cinc.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        <mhi@...ts.linux.dev>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_bbhatt@...cinc.com>, <loic.poulain@...aro.org>
Subject: Re: [PATCH 5/5] bus: mhi: host: Remove redundant dma_wmb() before ctx
 wp update


On 5/2/2022 3:41 AM, Manivannan Sadhasivam wrote:
> The endpoint device will only read the context wp when the host rings
> the doorbell. And moreover the doorbell write is using writel(). This
> guarantess that the prior writes will be completed before ringing
> doorbell.
>
> So there is no need of an additional dma_wmb() to order the coherent
> memory writes w.r.t each other. Even if the writes gets reordered, it
> won't affect the endpoint device.
>
> Cc: Loic Poulain <loic.poulain@...aro.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> Reviewed by: Hemant Kumar <quic_hemantk@...cinc.com>
>