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From: Vinod Koul <vkoul@kernel.org>
To: Alexey Minnekhanov <alexeymin@postmarketos.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Wolfram Sang <wsa@kernel.org>,
	linux-arm-msm@vger.kernel.org, Andy Gross <agross@kernel.org>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Douglas Anderson <dianders@chromium.org>,
	Matthias Kaehlcke <mka@chromium.org>,
	linux-i2c@vger.kernel.org
Subject: Re: [PATCH v4] i2c: qcom-geni: Add support for GPI DMA
Date: Wed, 3 Nov 2021 10:51:47 +0530	[thread overview]
Message-ID: <YYIca8877aa6hNmd@matsya> (raw)
In-Reply-To: <eb297333-63bb-91c4-6340-801c3c9e3663@postmarketos.org>

Hello Alexey,

On 03-11-21, 05:13, Alexey Minnekhanov wrote:
> 19.10.2021 09:01, Vinod Koul wrote:
> > This adds capability to use GSI DMA for I2C transfers
> > 
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> > Changes since v3:
> >   - remove separate tx and rx function for gsi dma and make a common one
> >   - remove global structs and use local variables instead
> > 
> 
> Hi, I've tried this patch on sm8150 board and I'm seeing weird things:
> 
> [    0.428829] gpi c00000.dma-controller: Adding to iommu group 0
> [    0.480453] geni_se_qup cc0000.geniqup: Adding to iommu group 1
> [    0.484019] geni_i2c c80000.i2c: Bus frequency not specified, default to
> 100kHz.
> [    0.487172] geni_i2c c80000.i2c: error 0000000000000000: Failed to get tx
> DMA ch
> [    0.495499] geni_i2c c80000.i2c: error 0000000000000000: Failed to get rx
> DMA ch
> [    0.499842] geni_i2c c80000.i2c: Grabbed GPI dma channels
> [    0.504784] geni_i2c c80000.i2c: Using GPI DMA mode for I2C
> [    0.510812] geni_i2c c80000.i2c: Geni-I2C adaptor successfully added
> 
> It seems weird to me that it "failed to get DMA channels", but then says
> anyway "Grabbed GPI DMA channels" and "Using GPI DMA mode for I2C".
> 
> What I did in dts is basically include sm8150.dtsi and do
> 
> &gpi_dma2 {
> 	status = "okay";
> };
> 
> &i2c17 {
> 	status = "okay";
> 	dmas = <&gpi_dma2 0 0 QCOM_GPI_I2C>,
> 		<&gpi_dma2 1 0 QCOM_GPI_I2C>;
> 	dma-names = "tx", "rx";
> 	/* empty - no clients */
> }
> 
> Another observation, even if I comment out "dmas" and "dma-names" in i2c17
> node, I get
> 
> [    0.487037] geni_i2c c80000.i2c: error (____ptrval____): Failed to get tx
> DMA ch
> [    0.490077] geni_i2c c80000.i2c: error (____ptrval____): Failed to get rx
> DMA ch
> [    0.493077] geni_i2c c80000.i2c: Grabbed GPI dma channels
> [    0.496061] geni_i2c c80000.i2c: Using GPI DMA mode for I2C
> [    0.500155] geni_i2c c80000.i2c: Geni-I2C adaptor successfully added

This does not look correct. In absence of dmas property, the channel
allocation should not have gone ahead and you should not see " Grabbed
GPI dma channels" message!

Btw what is the output of below when dmas was commented out:
cat /sys/kernel/debug/dmaengine/summary

This would show the channels allocated to each controller

-- 
~Vinod

  reply	other threads:[~2021-11-03  5:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-19  6:01 [PATCH v4] i2c: qcom-geni: Add support for GPI DMA Vinod Koul
2021-11-01 16:23 ` Bjorn Andersson
2021-11-03  2:13 ` Alexey Minnekhanov
2021-11-03  5:21   ` Vinod Koul [this message]
2021-11-04  2:44     ` Alexey Minnekhanov
2021-10-29 15:31 kernel test robot
2021-10-31 14:05 ` kernel test robot
2021-10-31 14:05   ` kernel test robot

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