Re: [PATCH v3 2/6] spi: bitbang: Implement support for MOSI idle state configuration

Nuno Sá
2024-06-05T09:26:51Z

On Tue, 2024-06-04 at 19:42 -0300, Marcelo Schmitt wrote:
> Some SPI peripherals may require strict MOSI line state when the controller
> is not clocking out data.
> Implement support for MOSI idle state configuration (low or high) by
> setting the data output line level on controller setup and after transfers.
> Bitbang operations now call controller specific set_mosi_idle() call back
> to set MOSI to its idle state.
> The MOSI line is kept at its idle state if no tx buffer is provided.
>
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
> ---

Some minor nit below in case a re-spin is needed. Anyways,

Acked-by: Nuno Sa <nuno.sa@analog.com>

>  drivers/spi/spi-bitbang.c       | 24 ++++++++++++++++++++++++
>  include/linux/spi/spi_bitbang.h |  1 +
>  2 files changed, 25 insertions(+)
>
> diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
> index ca5cc67555c5..3dee085d3570 100644
> --- a/drivers/spi/spi-bitbang.c
> +++ b/drivers/spi/spi-bitbang.c
> @@ -63,21 +63,28 @@ static unsigned bitbang_txrx_8(
>   unsigned flags
>  )
>  {
> + struct spi_bitbang *bitbang;
>   unsigned bits = t->bits_per_word;
>   unsigned count = t->len;
>   const u8 *tx = t->tx_buf;
>   u8 *rx = t->rx_buf;
>
> + bitbang = spi_controller_get_devdata(spi->controller);
>   while (likely(count > 0)) {
>   u8 word = 0;
>
>   if (tx)
>   word = *tx++;
> + else
> + word = (spi->mode & SPI_MOSI_IDLE_HIGH) ? 0xFF : 0;

no need for ()

>   word = txrx_word(spi, ns, word, bits, flags);
>   if (rx)
>   *rx++ = word;
>   count -= 1;
>   }
> + if (bitbang->set_mosi_idle)
> + bitbang->set_mosi_idle(spi);
> +
>   return t->len - count;
>  }
>
> @@ -92,21 +99,28 @@ static unsigned bitbang_txrx_16(
>   unsigned flags
>  )
>  {
> + struct spi_bitbang *bitbang;
>   unsigned bits = t->bits_per_word;
>   unsigned count = t->len;
>   const u16 *tx = t->tx_buf;
>   u16 *rx = t->rx_buf;
>
> + bitbang = spi_controller_get_devdata(spi->controller);
>   while (likely(count > 1)) {
>   u16 word = 0;
>
>   if (tx)
>   word = *tx++;
> + else
> + word = (spi->mode & SPI_MOSI_IDLE_HIGH) ? 0xFFFF : 0;

ditto (and for the txrx8 function)

- Nuno Sá