linux-kernel - [PATCH v4 2/2] media: rc: ir-spi: constrain carrier frequency

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Message-ID: <20250611112348.3576093-3-demonsingur@gmail.com>
Date: Wed, 11 Jun 2025 14:23:44 +0300
From: Cosmin Tanislav <demonsingur@...il.com>
To: 
Cc: Sean Young <sean@...s.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Cosmin Tanislav <demonsingur@...il.com>
Subject: [PATCH v4 2/2] media: rc: ir-spi: constrain carrier frequency

Carrier frequency is currently unconstrained, allowing the SPI transfer
to be allocated and filled only for it to be later rejected by the SPI
controller since the frequency is too large.

Add a check to constrain the carrier frequency inside
ir_spi_set_tx_carrier().

Also, move the number of bits per pulse to a macro since it is not used
in multiple places.

Signed-off-by: Cosmin Tanislav <demonsingur@...il.com>
---
 drivers/media/rc/ir-spi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/media/rc/ir-spi.c b/drivers/media/rc/ir-spi.c
index 50e30e2fae22..bf731204c81e 100644
--- a/drivers/media/rc/ir-spi.c
+++ b/drivers/media/rc/ir-spi.c
@@ -21,6 +21,7 @@
 #define IR_SPI_DRIVER_NAME		"ir-spi"
 
 #define IR_SPI_DEFAULT_FREQUENCY	38000
+#define IR_SPI_BITS_PER_PULSE		16
 
 struct ir_spi_data {
 	u32 freq;
@@ -70,7 +71,7 @@ static int ir_spi_tx(struct rc_dev *dev, unsigned int *buffer, unsigned int coun
 
 	memset(&xfer, 0, sizeof(xfer));
 
-	xfer.speed_hz = idata->freq * 16;
+	xfer.speed_hz = idata->freq * IR_SPI_BITS_PER_PULSE;
 	xfer.len = len * sizeof(*tx_buf);
 	xfer.tx_buf = tx_buf;
 
@@ -98,6 +99,9 @@ static int ir_spi_set_tx_carrier(struct rc_dev *dev, u32 carrier)
 	if (!carrier)
 		return -EINVAL;
 
+	if (carrier * IR_SPI_BITS_PER_PULSE > idata->spi->max_speed_hz)
+		return -EINVAL;
+
 	idata->freq = carrier;
 
 	return 0;
-- 
2.49.0