Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
In-Reply-To: <1680631400-28865-1-git-send-email-quic_vnivarth@quicinc.com>
References: <1680631400-28865-1-git-send-email-quic_vnivarth@quicinc.com>
From:   Stephen Boyd <swboyd@chromium.org>
User-Agent: alot/0.10
Date:   Tue, 4 Apr 2023 13:30:28 -0700
Message-ID: <CAE-0n52U7yG=5DzYiHCH=JR4LvdczvhpuaU3RXqX6K9VwfvEgw@mail.gmail.com>
Subject: Re: [PATCH 0/2] spi: Add DMA mode support to spi-qcom-qspi
To:     Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>,
        agross@kernel.org, andersson@kernel.org, broonie@kernel.org,
        devicetree@vger.kernel.org, konrad.dybcio@linaro.org,
        krzysztof.kozlowski+dt@linaro.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org,
        robh+dt@kernel.org, vkoul@kernel.org
Cc:     quic_msavaliy@quicinc.com, dianders@chromium.org, mka@chromium.org,
        quic_vtanuku@quicinc.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Quoting Vijaya Krishna Nivarthi (2023-04-04 11:03:18)
> There are large number of QSPI irqs that fire during boot/init and later
> on every suspend/resume.
> This could be made faster by doing DMA instead of PIO.
> Below is comparison for number of interrupts raised in 2 acenarios...
> Boot up and stabilise
> Suspend/Resume
>
> Sequence   PIO    DMA
> =======================
> Boot-up    69088  19284
> S/R        5066   3430
>

The interrupts are less, yes, but does it save time or power?