Re: [PATCH v1] Input: ads7846: do not overwrite spi->mode flags set by spi framework
From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2020-10-22 06:54:09
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On Wed, Oct 21, 2020 at 11:27:57AM -0700, Dmitry Torokhov wrote:
On Wed, Oct 21, 2020 at 12:56:14PM +0200, Oleksij Rempel wrote:quoted
As you can see, I would need to configure my dts with spi-cs-high flag, even if the hardware is actually ACTIVE_LOW. If I will go this way, I would risk a regression as soon as this issue is fixed. Since the spi framework is already parsing devicetree and set all needed flags, I assume it is wrong to blindly drop all this flags in the driver.Yes, but I wonder if the devices can only work in mode 0 we should be doing: spi->mode &= ~SPI_MODE_MASK; // to be defined as 0x03 in spi.h spi->mode |= SPI_MODE_0; as we can't simply "or" mode value as is
Why not? This values are taken from device tree. If some developer decided to add them, then driver should take it over. Even if this values will break the functionality. Other properties of this driver will break the functionality too of this driver too, so why should we silently filter only set of this bits?
(well, mode 0 is kind of working, but just on accident).
Good question, will be probably a good reason to measure it.
Thanks. -- Dmitry
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