tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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serial: add parameter to force skipping the test for the TXEN bug

Allow users to force skipping the TXEN test at init time. Applies
to all serial ports. Intended for debugging only.

There is a blacklist for devices where we need to skip the test but the
list is not complete. This lets users force skipping the test so we can
determine if they need to be added to the list.

Some HP machines with weird serial consoles have this problem and there
may be more.

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

authored by

Chuck Ebbert and committed by
Linus Torvalds d41a4b51 f23fc156

+6 -1
+6 -1
drivers/serial/8250.c
··· 64 64 return (serial8250_reg.minor - 64) + port->line; 65 65 } 66 66 67 + static unsigned int skip_txen_test; /* force skip of txen test at init time */ 68 + 67 69 /* 68 70 * Debugging. 69 71 */ ··· 2110 2108 is variable. So, let's just don't test if we receive 2111 2109 TX irq. This way, we'll never enable UART_BUG_TXEN. 2112 2110 */ 2113 - if (up->port.flags & UPF_NO_TXEN_TEST) 2111 + if (skip_txen_test || up->port.flags & UPF_NO_TXEN_TEST) 2114 2112 goto dont_test_tx_en; 2115 2113 2116 2114 /* ··· 3249 3247 3250 3248 module_param(nr_uarts, uint, 0644); 3251 3249 MODULE_PARM_DESC(nr_uarts, "Maximum number of UARTs supported. (1-" __MODULE_STRING(CONFIG_SERIAL_8250_NR_UARTS) ")"); 3250 + 3251 + module_param(skip_txen_test, uint, 0644); 3252 + MODULE_PARM_DESC(skip_txen_test, "Skip checking for the TXEN bug at init time"); 3252 3253 3253 3254 #ifdef CONFIG_SERIAL_8250_RSA 3254 3255 module_param_array(probe_rsa, ulong, &probe_rsa_count, 0444);