[PATCH v1 1/1] serial: 8250_mid: Disable DMA for selected platforms

[Andy Shevchenko]

In accordance with Errata (specification updates)
HSUART May Stop Functioning when DMA is Active.

- Denverton document #572409, rev 3.4, DNV60
- Ice Lake Xeon D document #714070, ICXD65
- Snowridge document #731931, SNR44

For a quick fix just disable the respective callbacks during the device probe.
Depending on the future development we might remove them completely.

Reported-by: micas-opensource <zjianan156@xxxxxxxxx>
Closes: https://lore.kernel.org/linux-serial/20250625031409.2404219-1-opensource@xxxxxxxxxxxxx/
Fixes: 6ede6dcd87aa ("serial: 8250_mid: add support for DMA engine handling from UART MMIO")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_mid.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mid.c b/drivers/tty/serial/8250/8250_mid.c
index 8ec03863606e..f88809ff370b 100644
--- a/drivers/tty/serial/8250/8250_mid.c
+++ b/drivers/tty/serial/8250/8250_mid.c
@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/rational.h>
+#include <linux/util_macros.h>
 
 #include <linux/dma/hsu.h>
 
@@ -368,8 +369,16 @@ static const struct mid8250_board dnv_board = {
 	.freq = 133333333,
 	.base_baud = 115200,
 	.bar = 1,
-	.setup = dnv_setup,
-	.exit = dnv_exit,
+	/*
+	 * Errata:
+	 * HSUART May Stop Functioning when DMA is Active.
+	 *
+	 * - Denverton document #572409, rev 3.4, DNV60
+	 * - Ice Lake Xeon D document #714070, ICXD65
+	 * - Snowridge document #731931, SNR44
+	 */
+	.setup = PTR_IF(false, dnv_setup),
+	.exit = PTR_IF(false, dnv_exit),
 };
 
 static const struct pci_device_id pci_ids[] = {
-- 
2.50.1