Re: [PATCH v3 5/6] spi: spi-engine-ex: Add support for multi-CS devices

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Aug 17, 2026 at 08:33:26PM -0300, Jonathan Santos wrote:
> The SPI Engine controller only handled the first chip select when
> asserting CS lines and configuring CS polarity inversion, ignoring
> additional CS indices present in cs_index_mask.
> 
> Update spi_engine_gen_cs() to iterate over all set bits in
> cs_index_mask and toggle each corresponding CS line in the assert mask.
> Update spi_engine_setup() likewise so that SPI_CS_HIGH polarity is
> applied to every active CS index rather than only index 0.
> 
> Set SPI_CONTROLLER_MULTI_CS in the controller flags to reflect the
> capability to the SPI core.

...

> +		for_each_set_bit(cs_bit, &cs_index_mask, SPI_ENGINE_MAX_CS)
> +			mask ^= BIT(spi_get_chipselect(spi, cs_bit));

> +	for_each_set_bit(cs_bit, &cs_index_mask, SPI_ENGINE_MAX_CS) {
> +		if (device->mode & SPI_CS_HIGH)
> +			spi_engine->cs_inv |= BIT(spi_get_chipselect(device, cs_bit));
> +		else
> +			spi_engine->cs_inv &= ~BIT(spi_get_chipselect(device, cs_bit));
> +	}

Looking at these two I would rather see a helper

unsigned long spi_get_chipselect_bits(..., unsigned long index_mask)

With that the above becomes for-loop free.

		mask ^= spi_get_chipselect_bits(spi, cs_index_mask);

and

	if (device->mode & SPI_CS_HIGH)
		spi_engine->cs_inv |= spi_get_chipselect_bits(device, cs_index_mask));
	else
		spi_engine->cs_inv &= ~spi_get_chipselect_bits(device, cs_index_mask));

respectively.

-- 
With Best Regards,
Andy Shevchenko