From: Pavel Machek <pavel@denx.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Serge Semin <Sergey.Semin@baikalelectronics.ru>,
Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>,
Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Arnd Bergmann <arnd@arndb.de>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Feng Tang <feng.tang@intel.com>, Rob Herring <robh+dt@kernel.org>,
linux-mips@vger.kernel.org, devicetree@vger.kernel.org,
Mark Brown <broonie@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 4.19 182/267] spi: dw: Return any value retrieved from the dma_transfer callback
Date: Fri, 19 Jun 2020 23:07:19 +0200 [thread overview]
Message-ID: <20200619210719.GB12233@amd> (raw)
In-Reply-To: <20200619141657.498868116@linuxfoundation.org>
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On Fri 2020-06-19 16:32:47, Greg Kroah-Hartman wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
>
> [ Upstream commit f0410bbf7d0fb80149e3b17d11d31f5b5197873e ]
>
> DW APB SSI DMA-part of the driver may need to perform the requested
> SPI-transfer synchronously. In that case the dma_transfer() callback
> will return 0 as a marker of the SPI transfer being finished so the
> SPI core doesn't need to wait and may proceed with the SPI message
> trasnfers pumping procedure. This will be needed to fix the problem
> when DMA transactions are finished, but there is still data left in
> the SPI Tx/Rx FIFOs being sent/received. But for now make dma_transfer
> to return 1 as the normal dw_spi_transfer_one() method.
As far as I understand, this is support for new SoC, not a fix?
> +++ b/drivers/spi/spi-dw.c
> @@ -383,11 +383,8 @@ static int dw_spi_transfer_one(struct spi_controller *master,
>
> spi_enable_chip(dws, 1);
>
> - if (dws->dma_mapped) {
> - ret = dws->dma_ops->dma_transfer(dws, transfer);
> - if (ret < 0)
> - return ret;
> - }
> + if (dws->dma_mapped)
> + return dws->dma_ops->dma_transfer(dws, transfer);
>
> if (chip->poll_mode)
> return poll_transfer(dws);
Mainline patch simply changes return value, but code is different in
v4.19, and poll_transfer will now be avoided when dws->dma_mapped. Is
that a problem?
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2020-06-19 21:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200619141648.840376470@linuxfoundation.org>
2020-06-19 14:31 ` [PATCH 4.19 110/267] spi: dw: Enable interrupts in accordance with DMA xfer mode Greg Kroah-Hartman
2020-06-19 14:31 ` [PATCH 4.19 111/267] clocksource: dw_apb_timer: Make CPU-affiliation being optional Greg Kroah-Hartman
2020-06-19 14:31 ` [PATCH 4.19 112/267] clocksource: dw_apb_timer_of: Fix missing clockevent timers Greg Kroah-Hartman
2020-06-19 14:31 ` [PATCH 4.19 117/267] spi: dw: Fix Rx-only DMA transfers Greg Kroah-Hartman
2020-06-19 14:32 ` [PATCH 4.19 182/267] spi: dw: Return any value retrieved from the dma_transfer callback Greg Kroah-Hartman
2020-06-19 21:07 ` Pavel Machek [this message]
2020-06-22 20:51 ` Serge Semin
2020-06-26 15:18 ` Ralph Siemsen
2020-06-26 20:07 ` Sasha Levin
2020-06-27 18:22 ` Ralph Siemsen
2020-06-29 14:26 ` Sasha Levin
2020-06-30 1:36 ` Ralph Siemsen
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