Re: [PATCH v2 2/2] spi: loongson: add bus driver for the loongson spi controller

[zhuyinbo]

在 2023/3/21 下午8:08, Mark Brown 写道:
> On Tue, Mar 21, 2023 at 10:54:32AM +0800, zhuyinbo wrote:
> > 在 2023/3/20 下午8:52, Mark Brown 写道:
> > > No, that doesn't help if setup() reconfigures the controller while it's
> > > doing a transfer.  The issue is that the controller might be put into
> > > the wrong mode or run at the wrong speed.
> > sorry, I don't got that why cpu still can call setup's critical region when
> > cpu call transfer_one to  transfer spi data.
> > when I added a spin_lock for setup and transfer_one then setup and
> > transfer_one's critical region cann't be called
> > simultaneously as I know, because the their lock was same lock.
> Think what happens if the two SPI devices have different configurations
> - for example, a different SPI mode.  The register state won't be
> corrupted but the devices will still end up seeing misconfigured SPI
> transfers.

I think add following change and that issue what you said will can be 
fixed,   in addition, the spin_lock

was also not needed.   Do you think so?

@@ -101,8 +101,10 @@ static int loongson_spi_setup(struct spi_device *spi)
        if (spi->chip_select >= spi->master->num_chipselect)
                return -EINVAL;

+       loongson_spi->hz = 0;
+       loongson_spi->mode &= SPI_NO_CS;
+
        spin_lock(&loongson_spi->lock);
-       loongson_spi_update_state(loongson_spi, spi, NULL);
        loongson_spi_set_cs(spi, 1);