On Mon, Feb 14, 2022 at 04:40:19PM +0800, Jon Lin wrote: > 在 2022/2/11 19:24, Mark Brown 写道: > > > + cr0 |= ((spi->mode & 0x3) << CR0_SCPH_OFFSET); > > > + if (spi->mode & SPI_CS_HIGH) > > > + cr0 |= BIT(spi->chip_select) << CR0_SOI_OFFSET; > > What ensures that this read/modify/write doesn't race with a transfer > > running on another client device in the case where the controller has > > more than one device connected? Similarly with the mode, though it's > > not great to have devices with different modes connected to a single > > controller. > I have no idea how to deal with the conflict configuration between > different cs, and also I find nothing strategy in others spi drivers. > As we all know, some configurations should be consistent for different > CS devices, such as SPI_CPOL, so I suggest the framework to make > corresponding early warning prompts. As covered in the documentation setup() for one device may run while another is active, therefore if multiple devices are configured in the same register you should use a lock to ensure there can't be multiple writes. Note that the above appears to not just be setting the mode but also the chip select so if you've got two SPI_CS_HIGH devices then they'll both be going in and separately setting cr0.
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