linux-kernel - Re: [PATCH RESEND 2/3] arm64: dts: qcom: sc8280xp: Add GPI DMA configuration

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Message-ID: <20250605131719.472132-1-mitltlatltl@gmail.com>
Date: Thu,  5 Jun 2025 21:17:18 +0800
From: Pengyu Luo <mitltlatltl@...il.com>
To: eugen.hristev@...aro.org
Cc: andersson@...nel.org,
	conor+dt@...nel.org,
	devicetree@...r.kernel.org,
	dmaengine@...r.kernel.org,
	dmitry.baryshkov@...ndries.io,
	konradybcio@...nel.org,
	krzk+dt@...nel.org,
	linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	mitltlatltl@...il.com,
	robh@...nel.org,
	vkoul@...nel.org
Subject: Re: [PATCH RESEND 2/3] arm64: dts: qcom: sc8280xp: Add GPI DMA configuration

On Thu, Jun 5, 2025 at 8:48 PM Eugen Hristev <eugen.hristev@...aro.org> wrote:
> On 6/5/25 10:54, Pengyu Luo wrote:
> > SPI on SC8280XP requires DMA (GSI) mode to function properly. Without it,
> > SPI controllers fall back to FIFO mode, which causes:
> >
> > [    0.901296] geni_spi 898000.spi: error -ENODEV: Failed to get tx DMA ch
> > [    0.901305] geni_spi 898000.spi: FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode
> > ...
> > [   45.605974] goodix-spi-hid spi0.0: SPI transfer timed out
> > [   45.605988] geni_spi 898000.spi: Can't set CS when prev xfer running
> > [   46.621555] spi_master spi0: failed to transfer one message from queue
> > [   46.621568] spi_master spi0: noqueue transfer failed
> > [   46.621577] goodix-spi-hid spi0.0: spi transfer error: -110
> > [   46.621585] goodix-spi-hid spi0.0: probe with driver goodix-spi-hid failed with error -110
> >
> > Therefore, add GPI DMA controller nodes for qup{0,1,2}, and add DMA
> > channels for SPI and I2C, UART is excluded for now, as it does not
> > yet support this mode.
> >
> > Note that, since there is no public schematic, this configuration
>
> Device tree should describe the hardware, not hold a configuration. If
> you are configuring hardware, DT is not the place for this. Same goes
> for the commit short message.
>

Since I am just an amateur, so I followed some applied examples, like [1]
If you mind this, I will describe in next version.

[1]: https://lore.kernel.org/linux-arm-msm/20241021102815.12079-1-quic_vdadhani@quicinc.com

Best wishes,
Pengyu