From: Linus Walleij <linus.walleij@linaro.org>
To: Serge Semin <Sergey.Semin@baikalelectronics.ru>,
Gregory Clement <gregory.clement@bootlin.com>
Cc: Mark Brown <broonie@kernel.org>,
Charles Keepax <ckeepax@opensource.cirrus.com>,
Serge Semin <fancer.lancer@gmail.com>,
Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>,
Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Paul Burton <paulburton@kernel.org>,
Ralf Baechle <ralf@linux-mips.org>, Arnd Bergmann <arnd@arndb.de>,
Allison Randal <allison@lohutok.net>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Gareth Williams <gareth.williams.jx@renesas.com>,
Rob Herring <robh+dt@kernel.org>,
linux-mips@vger.kernel.org,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
Phil Edworthy <phil.edworthy@renesas.com>,
Thomas Gleixner <tglx@linutronix.de>,
Alexios Zavras <alexios.zavras@intel.com>,
Thor Thayer <thor.thayer@linux.intel.com>,
"wuxu.wu" <wuxu.wu@huawei.com>,
Xinwei Kong <kong.kongxinwei@hisilicon.com>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
linux-spi <linux-spi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 11/17] spi: dw: Fix native CS being unset
Date: Fri, 8 May 2020 21:39:02 +0200 [thread overview]
Message-ID: <CACRpkdY=wkgnYPcqSzyzNpS6ckJZs-9kXfTfdwa1E+POzOBQGA@mail.gmail.com> (raw)
In-Reply-To: <20200508132943.9826-12-Sergey.Semin@baikalelectronics.ru>
On Fri, May 8, 2020 at 3:31 PM Serge Semin
<Sergey.Semin@baikalelectronics.ru> wrote:
> Commit 6e0a32d6f376 ("spi: dw: Fix default polarity of native
> chipselect") attempted to fix the problem when GPIO active-high
> chip-select is utilized to communicate with some SPI slave. It fixed
> the problem, but broke the normal native CS support. At the same time
> the reversion commit ada9e3fcc175 ("spi: dw: Correct handling of native
> chipselect") didn't solve the problem either, since it just inverted
> the set_cs() polarity perception without taking into account that
> CS-high might be applicable. Here is what is done to finally fix the
> problem.
I'm not sure this is the whole story.
I think Charles' fix made it work, and then commit
3e5ec1db8bfee845d9f8560d1c64aeaccd586398
"spi: Fix SPI_CS_HIGH setting when using native and GPIO CS"
fixed it broken again.
This commit will make sure only set SPI_CS_HIGH on a
spi_device if it is using a GPIO as CS. Before this change,
the core would set that on everything, and expect the
.set_cs() callback to cope.
I think we fixed that and that fix should have been undone
when applying commit 3e5ec1db8bfe.
So possibly Fixes: should be set only to this commit, so
that the fix is not backported to kernels without it.
> DW SPI controller demands any native CS being set in order to proceed
> with data transfer. So in order to activate the SPI communications we
> must set any bit in the Slave Select DW SPI controller register no
> matter whether the platform requests the GPIO- or native CS.
Ah-ha! Maybe we should even add a comment explaining that.
And that is why SPI_MASTER_GPIO_SS is set.
I suppose my naive understanding was:
"bit set to 1" = CS asserted (driven low)
"bit set to 0" = CS de-asserted (driven high)
So that is not how this register works at all.
> This commit fixes the problem for all described cases. So no matter
> whether an SPI slave needs GPIO- or native-based CS with active-high
> or low signal the corresponding bit will be set in SER.
Makes sense.
> struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
> struct chip_data *chip = spi_get_ctldata(spi);
> + bool cs_high = !!(spi->mode & SPI_CS_HIGH);
>
> /* Chip select logic is inverted from spi_set_cs() */
> if (chip && chip->cs_control)
> chip->cs_control(!enable);
>
> - if (!enable)
> + if (cs_high == enable)
> dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
This is the correct fix now but I an afraid not correct before
commit 3e5ec1db8bfe.
What I can't help but asking is: can the native chip select even
handle active high chip select if not backed by a GPIO?
Which register would set that polarity?
Yours,
Linus Walleij
next prev parent reply other threads:[~2020-05-08 19:39 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 13:29 [PATCH 00/17] spi: dw: Add generic DW DMA controller support Serge Semin
2020-05-08 13:29 ` [PATCH 01/17] dt-bindings: spi: Convert DW SPI binding to DT schema Serge Semin
2020-05-08 19:39 ` Andy Shevchenko
2020-05-12 20:28 ` Serge Semin
2020-05-12 20:35 ` Andy Shevchenko
2020-05-08 13:29 ` [PATCH 02/17] dt-bindings: spi: dw: Add DMA properties bindings Serge Semin
2020-05-08 13:29 ` [PATCH 04/17] spi: dw: Cleanup generic DW DMA code namings Serge Semin
2020-05-08 19:43 ` Andy Shevchenko
2020-05-12 21:26 ` Serge Semin
2020-05-12 21:37 ` Andy Shevchenko
2020-05-08 13:29 ` [PATCH 06/17] spi: dw: Add DW SPI DMA/PCI/MMIO dependency on DW SPI core Serge Semin
2020-05-08 13:29 ` [PATCH 08/17] spi: dw: Clear DMAC register when done or stopped Serge Semin
2020-05-08 17:31 ` Mark Brown
2020-05-13 11:56 ` Serge Semin
2020-05-08 13:29 ` [PATCH 09/17] spi: dw: Enable interrupts in accordance with DMA xfer mode Serge Semin
2020-05-08 13:29 ` [PATCH 10/17] spi: dw: Parameterize the DMA Rx/Tx burst length Serge Semin
2020-05-08 13:29 ` [PATCH 12/17] spi: dw: Fix dma_slave_config used partly uninitialized Serge Semin
2020-05-08 19:20 ` Andy Shevchenko
2020-05-08 13:29 ` [PATCH 13/17] spi: dw: Initialize paddr in DW SPI MMIO private data Serge Semin
2020-05-08 19:21 ` Andy Shevchenko
2020-05-13 12:30 ` Serge Semin
2020-05-08 13:33 ` [PATCH 00/17] spi: dw: Add generic DW DMA controller support Mark Brown
2020-05-12 20:07 ` Serge Semin
2020-05-13 10:23 ` Mark Brown
2020-05-13 11:04 ` Serge Semin
2020-05-13 11:21 ` Mark Brown
2020-05-13 11:42 ` Serge Semin
[not found] ` <20200508132943.9826-8-Sergey.Semin@baikalelectronics.ru>
2020-05-08 17:30 ` [PATCH 07/17] spi: dw: Add Tx/Rx finish wait methods to DMA Mark Brown
[not found] ` <20200513113555.mjivjk374giopnea@mobilestation>
2020-05-13 11:36 ` Mark Brown
2020-05-08 17:36 ` [PATCH 00/17] spi: dw: Add generic DW DMA controller support Mark Brown
2020-05-08 19:16 ` Andy Shevchenko
2020-05-12 20:34 ` Serge Semin
2020-05-12 20:30 ` Serge Semin
[not found] ` <20200508132943.9826-15-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:23 ` [PATCH 14/17] spi: dw: Add DMA support to the DW SPI MMIO driver Andy Shevchenko
[not found] ` <20200508132943.9826-17-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:27 ` [PATCH 16/17] spi: dw: Fix Rx-only DMA transfers Andy Shevchenko
[not found] ` <20200508132943.9826-18-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:30 ` [PATCH 17/17] spi: dw: Use regset32 DebugFS method to create a registers file Andy Shevchenko
[not found] ` <20200513124422.z6ctlmvipwer45q4@mobilestation>
2020-05-13 14:41 ` Andy Shevchenko
2020-05-08 19:33 ` [PATCH 00/17] spi: dw: Add generic DW DMA controller support Andy Shevchenko
[not found] ` <20200508132943.9826-12-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:39 ` Linus Walleij [this message]
[not found] ` <20200513001347.dyt357erev7vzy3l@mobilestation>
2020-05-14 8:31 ` [PATCH 11/17] spi: dw: Fix native CS being unset Linus Walleij
[not found] ` <20200514115558.e6cqnuxqyqkysfn7@mobilestation>
2020-05-14 12:22 ` Andy Shevchenko
2020-05-14 13:03 ` Mark Brown
2020-05-14 14:35 ` Mark Brown
[not found] ` <20200508132943.9826-4-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:41 ` [PATCH 03/17] spi: dw: Split up the generic DMA code and Intel MID driver Andy Shevchenko
[not found] ` <20200508132943.9826-6-Sergey.Semin@baikalelectronics.ru>
2020-05-08 19:44 ` [PATCH 05/17] spi: dw: Discard static DW DMA slave structures Andy Shevchenko
2020-05-15 10:47 ` [PATCH v2 00/19] spi: dw: Add generic DW DMA controller support Serge Semin
2020-05-15 10:47 ` [PATCH v2 01/19] dt-bindings: spi: dw: Add Tx/Rx DMA properties Serge Semin
2020-05-15 11:51 ` Andy Shevchenko
2020-05-15 12:27 ` Mark Brown
2020-05-15 15:43 ` Serge Semin
2020-05-15 10:47 ` [PATCH v2 03/19] spi: dw: Clear DMAC register when done or stopped Serge Semin
2020-05-15 12:01 ` Andy Shevchenko
2020-05-15 16:42 ` Mark Brown
2020-05-15 17:21 ` Serge Semin
2020-05-15 10:47 ` [PATCH v2 05/19] spi: dw: Enable interrupts in accordance with DMA xfer mode Serge Semin
2020-05-15 12:27 ` Andy Shevchenko
2020-05-16 14:06 ` Serge Semin
2020-05-15 10:47 ` [PATCH v2 09/19] spi: dw: Parameterize the DMA Rx/Tx burst length Serge Semin
2020-05-15 14:01 ` Andy Shevchenko
[not found] ` <20200516143353.hw6nny5hbwgiyxfw@mobilestation>
2020-05-18 11:01 ` Andy Shevchenko
2020-05-18 12:41 ` Serge Semin
2020-05-15 10:47 ` [PATCH v2 10/19] spi: dw: Use DMA max burst to set the request thresholds Serge Semin
2020-05-15 14:38 ` Andy Shevchenko
[not found] ` <20200516200133.wmaqnfjbr7234fzo@mobilestation>
2020-05-18 11:03 ` Andy Shevchenko
2020-05-18 12:43 ` Mark Brown
2020-05-18 12:52 ` Serge Semin
2020-05-18 13:25 ` Andy Shevchenko
2020-05-18 13:43 ` Serge Semin
2020-05-18 14:48 ` Andy Shevchenko
2020-05-18 14:59 ` Serge Semin
2020-05-15 10:47 ` [PATCH v2 11/19] spi: dw: Initialize paddr in DW SPI MMIO private data Serge Semin
2020-05-15 14:39 ` Andy Shevchenko
2020-05-15 10:47 ` [PATCH v2 14/19] spi: dw: Remove DW DMA code dependency from DW_DMAC_PCI Serge Semin
2020-05-15 15:02 ` Andy Shevchenko
2020-05-15 10:47 ` [PATCH v2 15/19] spi: dw: Add DW SPI DMA/PCI/MMIO dependency on the DW SPI core Serge Semin
2020-05-15 15:03 ` Andy Shevchenko
2020-05-15 10:47 ` [PATCH v2 17/19] spi: dw: Add DMA support to the DW SPI MMIO driver Serge Semin
2020-05-15 15:08 ` Andy Shevchenko
2020-05-15 10:47 ` [PATCH v2 19/19] dt-bindings: spi: Convert DW SPI binding to DT schema Serge Semin
2020-05-16 20:59 ` Serge Semin
2020-05-15 11:49 ` [PATCH v2 00/19] spi: dw: Add generic DW DMA controller support Andy Shevchenko
2020-05-15 15:30 ` Serge Semin
[not found] ` <20200515104758.6934-3-Sergey.Semin@baikalelectronics.ru>
2020-05-15 12:01 ` [PATCH v2 02/19] spi: dw: Add Tx/Rx finish wait methods to the MID DMA Andy Shevchenko
2020-05-15 12:18 ` Mark Brown
2020-05-15 12:37 ` Andy Shevchenko
2020-05-15 12:41 ` Mark Brown
[not found] ` <20200515200250.zjsv5uaftwqcnwud@mobilestation>
2020-05-18 10:51 ` Mark Brown
[not found] ` <20200518110453.w3ko5a5yzwyr73ir@mobilestation>
2020-05-18 11:11 ` Mark Brown
[not found] ` <20200515194058.pmpd4wa7lw2dle3g@mobilestation>
2020-05-18 10:55 ` Andy Shevchenko
[not found] ` <20200515104758.6934-5-Sergey.Semin@baikalelectronics.ru>
2020-05-15 12:05 ` [PATCH v2 04/19] spi: dw: Fix native CS being unset Andy Shevchenko
[not found] ` <20200515104758.6934-7-Sergey.Semin@baikalelectronics.ru>
2020-05-15 12:34 ` [PATCH v2 06/19] spi: dw: Discard static DW DMA slave structures Andy Shevchenko
[not found] ` <20200516142030.kburieaxjg4n7c42@mobilestation>
2020-05-18 11:00 ` Andy Shevchenko
2020-05-18 11:38 ` Andy Shevchenko
[not found] ` <20200518123242.xoosc4pcj7heo4he@mobilestation>
2020-05-18 13:22 ` Andy Shevchenko
[not found] ` <20200515104758.6934-8-Sergey.Semin@baikalelectronics.ru>
2020-05-15 12:38 ` [PATCH v2 07/19] spi: dw: Discard unused void priv pointer Andy Shevchenko
[not found] ` <20200515104758.6934-9-Sergey.Semin@baikalelectronics.ru>
2020-05-15 13:03 ` [PATCH v2 08/19] spi: dw: Discard dma_width member of the dw_spi structure Andy Shevchenko
[not found] ` <20200515130559.psq2zwfhovt6rzhl@mobilestation>
2020-05-15 13:49 ` Andy Shevchenko
[not found] ` <20200515141627.pqdaic6wksatusl6@mobilestation>
2020-05-15 15:00 ` Andy Shevchenko
[not found] ` <20200515104758.6934-13-Sergey.Semin@baikalelectronics.ru>
2020-05-15 14:40 ` [PATCH v2 12/19] spi: dw: Fix Rx-only DMA transfers Andy Shevchenko
2020-05-15 16:55 ` Mark Brown
[not found] ` <20200515104758.6934-14-Sergey.Semin@baikalelectronics.ru>
2020-05-15 14:51 ` [PATCH v2 13/19] spi: dw: Move Non-DMA code to the DW PCIe-SPI driver Andy Shevchenko
[not found] ` <20200516201724.7q5uhxmzpr6xjooj@mobilestation>
[not found] ` <20200518125850.jnhaqlr2ticu3ivs@mobilestation>
2020-05-18 13:00 ` Mark Brown
[not found] ` <20200515104758.6934-19-Sergey.Semin@baikalelectronics.ru>
2020-05-15 15:10 ` [PATCH v2 18/19] spi: dw: Use regset32 DebugFS method to create regdump file Andy Shevchenko
[not found] ` <20200516204634.td52orxfnh7iewg6@mobilestation>
2020-05-18 11:18 ` Andy Shevchenko
[not found] ` <20200518140825.jnkfpybxnwq7fx2m@mobilestation>
2020-05-18 15:06 ` Andy Shevchenko
2020-05-15 18:21 ` [PATCH v2 00/19] spi: dw: Add generic DW DMA controller support Mark Brown
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