From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v2 4/4] spi: spi-davinci: Add support for SPI_CS_WORD To: Geert Uytterhoeven Cc: linux-spi , linux-iio@vger.kernel.org, Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald , Mark Brown , Linux Kernel Mailing List References: <20180913003920.30600-1-david@lechnology.com> <20180913003920.30600-5-david@lechnology.com> From: David Lechner Message-ID: Date: Thu, 13 Sep 2018 09:26:48 -0500 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed List-ID: On 09/13/2018 08:44 AM, Geert Uytterhoeven wrote: > Hi David, > > On Thu, Sep 13, 2018 at 2:40 AM David Lechner wrote: >> This adds support for the SPI_CS_WORD flag to the TI DaVinci SPI >> driver. This mode can be used as long as we are using the hardware >> chip select and not a GPIO chip select. >> >> Signed-off-by: David Lechner >> --- >> drivers/spi/spi-davinci.c | 11 ++++++++--- >> 1 file changed, 8 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c >> index d502cf504deb..8f7dcbc53c57 100644 >> --- a/drivers/spi/spi-davinci.c >> +++ b/drivers/spi/spi-davinci.c >> @@ -230,7 +230,8 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value) >> !(spi->mode & SPI_CS_HIGH)); >> } else { >> if (value == BITBANG_CS_ACTIVE) { >> - spidat1 |= SPIDAT1_CSHOLD_MASK; >> + if (!(spi->mode & SPI_CS_WORD)) >> + spidat1 |= SPIDAT1_CSHOLD_MASK; >> spidat1 &= ~(0x1 << chip_sel); >> } >> } >> @@ -440,8 +441,12 @@ static int davinci_spi_setup(struct spi_device *spi) >> return retval; >> } >> >> - if (internal_cs) >> + if (internal_cs) { >> set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select); >> + } else if (spi->mode & SPI_CS_WORD) { >> + dev_err(&spi->dev, "SPI_CS_WORD can't be use with GPIO CS\n"); >> + return -EINVAL; > > Does the SPI core fall back to splitting the transfer in this case? Hmm... it doesn't look like it. I suppose it might be best to modify the SPI core to say: if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) || gpio_is_valid(spi->cs_gpio)) { instead of: if ((spi->mode & SPI_CS_WORD) && !(ctlr->mode_bits & SPI_CS_WORD)) { Then we could drop the error above. > >> + } > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds >