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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Mark Brown <broonie@kernel.org>,
	linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH v1 1/2] spi: Allow to have all native CSs in use along with GPIOs
Date: Tue, 20 Apr 2021 17:10:03 +0300
Message-ID: <20210420141004.59936-1-andriy.shevchenko@linux.intel.com> (raw)

The commit 7d93aecdb58d ("spi: Add generic support for unused native cs
with cs-gpios") excludes the valid case for the controllers that doesn't
need to switch native CS in order to perform the transfer, i.e. when

  0		native
  ...		...
  <n> - 1	native
  <n>		GPIO
  <n> + 1	GPIO
  ...		...

where <n> defines maximum of native CSs supported by the controller.

To allow this, bail out from spi_get_gpio_descs() conditionally for
the controllers which explicitly marked with SPI_MASTER_GPIO_SS.

Fixes: 7d93aecdb58d ("spi: Add generic support for unused native cs with cs-gpios")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/spi/spi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 36c46feab6d4..9c3730a9f7d5 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2610,8 +2610,9 @@ static int spi_get_gpio_descs(struct spi_controller *ctlr)
 	}
 
 	ctlr->unused_native_cs = ffz(native_cs_mask);
-	if (num_cs_gpios && ctlr->max_native_cs &&
-	    ctlr->unused_native_cs >= ctlr->max_native_cs) {
+
+	if ((ctlr->flags & SPI_MASTER_GPIO_SS) && num_cs_gpios &&
+	    ctlr->max_native_cs && ctlr->unused_native_cs >= ctlr->max_native_cs) {
 		dev_err(dev, "No unused native chip select available\n");
 		return -EINVAL;
 	}
-- 
2.30.2


             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20 14:10 Andy Shevchenko [this message]
2021-04-20 14:10 ` [PATCH v1 2/2] spi: Avoid potential UB when counting unused native CSs Andy Shevchenko
2021-04-20 14:56   ` Mark Brown
2021-04-20 15:07     ` Andy Shevchenko
2021-04-20 15:22       ` Mark Brown

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