From: Mark Brown <broonie@kernel.org>
To: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
linux-riscv@lists.infradead.org, Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
devicetree@vger.kernel.org, Serge Semin <fancer.lancer@gmail.com>,
linux-spi@vger.kernel.org, Stephen Boyd <sboyd@kernel.org>,
linux-clk@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
linux-gpio@vger.kernel.org,
Philipp Zabel <p.zabel@pengutronix.de>,
Sean Anderson <seanga2@gmail.com>
Subject: Re: [PATCH 03/32] spi: dw: Fix driving MOSI low while recieving
Date: Mon, 9 Nov 2020 13:29:35 +0000 [thread overview]
Message-ID: <20201109132935.GB6380@sirena.org.uk> (raw)
In-Reply-To: <20201107081420.60325-4-damien.lemoal@wdc.com>
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On Sat, Nov 07, 2020 at 05:13:51PM +0900, Damien Le Moal wrote:
> The resting state of MOSI is high when nothing is driving it. If we
> drive it low while recieving, it looks like we are transmitting 0x00
> instead of transmitting nothing. This can confuse slaves (like SD cards)
> which allow new commands to be sent over MOSI while they are returning
> data over MISO. The return of MOSI from 0 to 1 at the end of recieving
> a byte can look like a start bit and a transmission bit to an SD card.
If client devices are interpreting the transmitted data then I would
expect the drivers for that hardware to be ensuring that whatever we
transmit matches what the device is expecting. We shouldn't be putting
a hack in a particular controller driver to paper over things, that will
mean that the device will break when used with other controllers and if
different devices have different requirements then obviously we can't
satisfy them. There is not meaningfully a general specification for SPI
which says what happens when signals are idle, it's all specific to the
client device.
In this case it also looks like the controller hardware requires
transmit data and therefore should be setting SPI_MUST_TX and just
removing the in driver default anyway, though that will have no effect
one way or anther on the issue you're seeing.
Please also try to avoid the use of master/slave terminology where
reasonable, controller and device tend to work for SPI (though MOSI/MISO
are going to be harder to shift).
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next prev parent reply other threads:[~2020-11-09 13:29 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-07 8:13 [PATCH 00/32] RISC-V Kendryte K210 support improvments Damien Le Moal
2020-11-07 8:13 ` [PATCH 01/32] of: Fix property supplier parsing Damien Le Moal
2020-11-09 15:05 ` Serge Semin
2020-11-09 15:14 ` Andy Shevchenko
2020-11-09 17:44 ` Serge Semin
2020-11-09 20:52 ` Rob Herring
2020-11-07 8:13 ` [PATCH 02/32] spi: dw: Add support for 32-bits ctrlr0 layout Damien Le Moal
2020-11-07 13:28 ` Sean Anderson
2020-11-09 14:25 ` Serge Semin
2020-11-09 14:33 ` Sean Anderson
2020-11-09 14:35 ` Sean Anderson
2020-11-09 14:40 ` Andy Shevchenko
2020-11-09 14:41 ` Andy Shevchenko
2020-11-09 14:49 ` Sean Anderson
2020-11-09 15:10 ` Andy Shevchenko
2020-11-09 14:36 ` Andy Shevchenko
2020-11-09 17:56 ` Serge Semin
2020-11-07 8:13 ` [PATCH 03/32] spi: dw: Fix driving MOSI low while recieving Damien Le Moal
2020-11-07 13:30 ` Sean Anderson
2020-11-09 13:29 ` Mark Brown [this message]
2020-11-09 13:47 ` Sean Anderson
2020-11-09 14:14 ` Mark Brown
2020-11-09 14:48 ` Serge Semin
2020-11-09 16:45 ` Mark Brown
2020-11-09 19:19 ` Serge Semin
2020-11-09 19:40 ` Sean Anderson
2020-11-09 20:17 ` Serge Semin
2020-11-09 20:29 ` Mark Brown
2020-11-09 20:20 ` Mark Brown
2020-11-09 21:05 ` Serge Semin
2020-11-10 13:43 ` Mark Brown
2020-11-07 8:13 ` [PATCH 04/32] spi: dw: Introduce polling device tree property Damien Le Moal
2020-11-09 16:04 ` Mark Brown
2020-11-09 19:59 ` Serge Semin
2020-11-13 9:22 ` Damien Le Moal
2020-11-15 16:01 ` Serge Semin
2020-11-16 7:47 ` Damien Le Moal
2020-11-16 12:33 ` Mark Brown
2020-11-16 21:55 ` Serge Semin
2020-11-17 14:44 ` Damien Le Moal
2020-11-17 18:26 ` Serge Semin
2020-11-18 4:41 ` Damien Le Moal
2020-11-18 15:16 ` Serge Semin
2020-11-19 5:12 ` Damien Le Moal
2020-11-19 8:51 ` Serge Semin
2020-11-19 8:57 ` Damien Le Moal
2020-11-07 8:13 ` [PATCH 05/32] spi: dw: Introduce DW_SPI_CAP_POLL_NODELAY Damien Le Moal
2020-11-09 14:03 ` Mark Brown
2020-11-09 20:45 ` Serge Semin
2020-11-07 8:13 ` [PATCH 06/32] spi: dw: Add support for the Kendryte K210 SoC Damien Le Moal
2020-11-07 13:31 ` Sean Anderson
2020-11-07 13:42 ` Damien Le Moal
2020-11-07 13:52 ` Sean Anderson
2020-11-09 14:15 ` Mark Brown
2020-11-13 8:00 ` Damien Le Moal
2020-11-09 21:21 ` Serge Semin
2020-11-09 21:39 ` Damien Le Moal
2020-11-09 21:55 ` Rob Herring
2020-11-09 22:00 ` Damien Le Moal
2020-11-09 23:07 ` Rob Herring
2020-11-10 0:35 ` Damien Le Moal
2020-11-07 8:13 ` [PATCH 07/32] dt-bindings: Update DW SPI device tree bindings Damien Le Moal
2020-11-07 8:13 ` [PATCH 08/32] riscv: Fix kernel time_init() Damien Le Moal
2020-11-12 7:21 ` Atish Patra
2020-11-13 7:31 ` Stephen Boyd
2020-11-07 8:13 ` [PATCH 09/32] riscv: Fix SiFive gpio probe Damien Le Moal
2020-11-10 14:39 ` Linus Walleij
2020-11-07 8:13 ` [PATCH 10/32] riscv: Fix sifive serial driver Damien Le Moal
2020-11-07 8:13 ` [PATCH 11/32] riscv: Enable interrupts during syscalls with M-Mode Damien Le Moal
2020-11-07 8:14 ` [PATCH 12/32] riscv: Automatically select sysctl config options Damien Le Moal
2020-11-07 8:14 ` [PATCH 13/32] riscv: Fix builtin DTB handling Damien Le Moal
2020-11-15 4:17 ` kernel test robot
2020-11-07 8:14 ` [PATCH 14/32] dt-bindings: Define all Kendryte K210 clock IDs Damien Le Moal
2020-11-07 13:33 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 15/32] dt-bindings: Define Kendryte K210 sysctl registers Damien Le Moal
2020-11-07 13:34 ` Sean Anderson
2020-11-09 21:59 ` Rob Herring
2020-11-09 22:10 ` Sean Anderson
2020-11-09 23:01 ` Rob Herring
2020-11-07 8:14 ` [PATCH 16/32] dt-bindings: Define Kendryte K210 pin functions Damien Le Moal
2020-11-07 13:38 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 17/32] dt-bindings: Define Kendryte K210 reset signals Damien Le Moal
2020-11-07 13:38 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 18/32] riscv: Add Kendryte K210 SoC clock driver Damien Le Moal
2020-11-07 13:48 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 19/32] riscv: Add Kendryte K210 SoC reset controller Damien Le Moal
2020-11-07 13:58 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 20/32] riscv: Add Kendryte K210 FPIOA pinctrl driver Damien Le Moal
2020-11-09 18:48 ` kernel test robot
2020-11-15 0:28 ` kernel test robot
2020-11-24 8:43 ` Linus Walleij
2020-11-24 8:53 ` Damien Le Moal
2020-11-29 21:33 ` Linus Walleij
2020-11-30 3:13 ` Damien Le Moal
2020-11-30 7:05 ` Serge Semin
2020-11-30 7:27 ` Damien Le Moal
2020-11-24 8:56 ` Damien Le Moal
2020-11-07 8:14 ` [PATCH 21/32] dt-bindings: Add Kendryte and Canaan vendor prefix Damien Le Moal
2020-11-07 14:03 ` Sean Anderson
2020-11-13 8:17 ` Damien Le Moal
2020-11-09 22:01 ` Rob Herring
2020-11-09 22:04 ` Damien Le Moal
2020-11-07 8:14 ` [PATCH 22/32] dt-binding: Document kendryte,k210-sysctl bindings Damien Le Moal
2020-11-07 14:05 ` Sean Anderson
2020-11-09 15:32 ` Rob Herring
2020-11-07 8:14 ` [PATCH 23/32] dt-binding: Document kendryte,k210-clk bindings Damien Le Moal
2020-11-07 14:05 ` Sean Anderson
2020-11-09 21:58 ` Rob Herring
2020-11-07 8:14 ` [PATCH 24/32] dt-bindings: Document kendryte,k210-fpioa bindings Damien Le Moal
2020-11-07 14:06 ` Sean Anderson
2020-11-09 15:32 ` Rob Herring
2020-11-09 15:36 ` Rob Herring
2020-11-09 15:45 ` Sean Anderson
2020-11-11 14:32 ` Rob Herring
2020-11-19 10:57 ` Geert Uytterhoeven
2020-11-19 11:22 ` Damien Le Moal
2020-11-07 8:14 ` [PATCH 25/32] dt-bindings: Document kendryte,k210-rst bindings Damien Le Moal
2020-11-07 14:07 ` Sean Anderson
2020-11-09 15:37 ` Rob Herring
2020-11-09 15:41 ` Rob Herring
2020-11-07 8:14 ` [PATCH 26/32] riscv: Update Kendryte K210 device tree Damien Le Moal
2020-11-07 14:08 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 27/32] riscv: Add SiPeed MAIX BiT board " Damien Le Moal
2020-11-07 14:13 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 28/32] riscv: Add SiPeed MAIX DOCK " Damien Le Moal
2020-11-07 8:14 ` [PATCH 29/32] riscv: Add SiPeed MAIX GO " Damien Le Moal
2020-11-07 8:14 ` [PATCH 30/32] riscv: Add SiPeed MAIXDUINO " Damien Le Moal
2020-11-07 14:14 ` Sean Anderson
2020-11-07 8:14 ` [PATCH 31/32] riscv: Add Kendryte KD233 " Damien Le Moal
2020-11-07 8:14 ` [PATCH 32/32] riscv: Update Kendryte K210 defconfig Damien Le Moal
2020-11-09 12:51 ` [PATCH 00/32] RISC-V Kendryte K210 support improvments Mark Brown
2020-11-09 12:55 ` Damien Le Moal
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