From: Stephan Gerhold <stephan@gerhold.net>
To: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Cc: Mark Brown <broonie@kernel.org>, Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
linux-arm-msm@vger.kernel.org, linux-spi@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] spi: qup: Vote for interconnect bandwidth to DRAM
Date: Wed, 13 Sep 2023 11:26:12 +0200 [thread overview]
Message-ID: <ZQGANOwy97w0RIHV@gerhold.net> (raw)
In-Reply-To: <20230912-spi-qup-dvfs-v1-4-3e38aa09c2bd@kernkonzept.com>
On Tue, Sep 12, 2023 at 04:30:39PM +0200, Stephan Gerhold wrote:
> When the SPI QUP controller is used together with a DMA engine it needs
> to vote for the interconnect path to the DRAM. Otherwise it may be
> unable to access the memory quickly enough.
I realized that I argue here that the interconnect vote is for DMA to
DRAM...
> [...]
> @@ -675,6 +698,12 @@ static int spi_qup_io_prep(struct spi_device *spi, struct spi_transfer *xfer)
> return -EIO;
> }
>
> + ret = spi_qup_vote_bw(controller, xfer->speed_hz);
> + if (ret) {
> + dev_err(controller->dev, "fail to vote for ICC bandwidth: %d\n", ret);
> + return -EIO;
> + }
> +
... but here I vote for the bandwidth even if PIO is used instead of DMA.
I think it would be more logical to only do the bandwidth vote in the
DMA setup path. I'll fix this in v2.
Thanks,
Stephan
prev parent reply other threads:[~2023-09-13 9:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-12 14:30 [PATCH 0/4] spi: qup: Allow scaling power domains and interconnect Stephan Gerhold
2023-09-12 14:30 ` [PATCH 1/4] spi: dt-bindings: qup: Document power-domains and OPP Stephan Gerhold
2023-09-13 8:18 ` Krzysztof Kozlowski
2023-09-12 14:30 ` [PATCH 2/4] spi: qup: Parse OPP table for DVFS support Stephan Gerhold
2023-09-13 8:54 ` Konrad Dybcio
2023-09-12 14:30 ` [PATCH 3/4] spi: dt-bindings: qup: Document interconnects Stephan Gerhold
2023-09-13 8:19 ` Krzysztof Kozlowski
2023-09-12 14:30 ` [PATCH 4/4] spi: qup: Vote for interconnect bandwidth to DRAM Stephan Gerhold
2023-09-13 9:26 ` Stephan Gerhold [this message]
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