[PATCH v2] spi: mediatek: single device does not require cs_gpios

From: Nicolas Boichat
Date: Sun Nov 08 2015 - 23:15:50 EST


When only one device is present, it is not necessary to specify
cs_gpios, as the CS line can be controlled by the hardware
module.

Without this patch, older device tree bindings used before
37457607 "spi: mediatek: mt8173 spi multiple devices support"
would cause a panic on boot. This fixes the crash, and
re-introduces backward compatibility.

Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx>
---

v2: Use gpio_is_valid()

Applies on top of broonie/spi.git/for-next.

drivers/spi/spi-mt65xx.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 563954a..7840067 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -410,7 +410,7 @@ static int mtk_spi_setup(struct spi_device *spi)
if (!spi->controller_data)
spi->controller_data = (void *)&mtk_default_chip_info;

- if (mdata->dev_comp->need_pad_sel)
+ if (mdata->dev_comp->need_pad_sel && gpio_is_valid(spi->cs_gpio))
gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));

return 0;
@@ -632,13 +632,23 @@ static int mtk_spi_probe(struct platform_device *pdev)
goto err_put_master;
}

- for (i = 0; i < master->num_chipselect; i++) {
- ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
- dev_name(&pdev->dev));
- if (ret) {
- dev_err(&pdev->dev,
- "can't get CS GPIO %i\n", i);
- goto err_put_master;
+ if (!master->cs_gpios && master->num_chipselect > 1) {
+ dev_err(&pdev->dev,
+ "cs_gpios not specified and num_chipselect > 1\n");
+ ret = -EINVAL;
+ goto err_put_master;
+ }
+
+ if (master->cs_gpios) {
+ for (i = 0; i < master->num_chipselect; i++) {
+ ret = devm_gpio_request(&pdev->dev,
+ master->cs_gpios[i],
+ dev_name(&pdev->dev));
+ if (ret) {
+ dev_err(&pdev->dev,
+ "can't get CS GPIO %i\n", i);
+ goto err_put_master;
+ }
}
}
}
--
2.6.0.rc2.230.g3dd15c0

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