diff options
author | Sean Young <sean@mess.org> | 2017-11-08 16:19:45 -0500 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-11-15 08:57:34 -0500 |
commit | 30b4e122d71cbec2944a5f8b558b88936ee42f10 (patch) | |
tree | d9502baa72354fa85ff8aae9cdd4062d16147b71 /drivers/media/rc | |
parent | f2ecc3d0787e05d9145722feed01d4a11ab6bec1 (diff) | |
download | op-kernel-dev-30b4e122d71cbec2944a5f8b558b88936ee42f10.zip op-kernel-dev-30b4e122d71cbec2944a5f8b558b88936ee42f10.tar.gz |
media: rc: sir_ir: detect presence of port
Without this test, sir_ir clumsy claims resources for a device which
does not exist.
The 0-day kernel test robot reports the following errors (in a loop):
sir_ir sir_ir.0: Trapped in interrupt
genirq: Flags mismatch irq 4. 00000000 (ttyS0) vs. 00000000 (sir_ir)
When sir_ir is loaded with the default io and irq, the following happens:
- sir_ir claims irq 4
- user space opens /dev/ttyS0
- in serial8250_do_startup(), some setup is done for ttyS0, which causes
irq 4 to fire (in THRE test)
- sir_ir does not realise it was not for it, and spins until the "trapped
in interrupt"
- now serial driver calls setup_irq() and fails and we get the
"Flags mismatch" error.
There is no port present at 0x3e8 so simply check for the presence of a
port, as suggested by Linus.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Sean Young <sean@mess.org>
Cc: <stable@vger.kernel.org> # 4.12+
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'drivers/media/rc')
-rw-r--r-- | drivers/media/rc/sir_ir.c | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/drivers/media/rc/sir_ir.c b/drivers/media/rc/sir_ir.c index 7612066..9ee2c91 100644 --- a/drivers/media/rc/sir_ir.c +++ b/drivers/media/rc/sir_ir.c @@ -57,7 +57,7 @@ static void add_read_queue(int flag, unsigned long val); static irqreturn_t sir_interrupt(int irq, void *dev_id); static void send_space(unsigned long len); static void send_pulse(unsigned long len); -static void init_hardware(void); +static int init_hardware(void); static void drop_hardware(void); /* Initialisation */ @@ -263,11 +263,36 @@ static void send_pulse(unsigned long len) } } -static void init_hardware(void) +static int init_hardware(void) { + u8 scratch, scratch2, scratch3; unsigned long flags; spin_lock_irqsave(&hardware_lock, flags); + + /* + * This is a simple port existence test, borrowed from the autoconfig + * function in drivers/tty/serial/8250/8250_port.c + */ + scratch = sinp(UART_IER); + soutp(UART_IER, 0); +#ifdef __i386__ + outb(0xff, 0x080); +#endif + scratch2 = sinp(UART_IER) & 0x0f; + soutp(UART_IER, 0x0f); +#ifdef __i386__ + outb(0x00, 0x080); +#endif + scratch3 = sinp(UART_IER) & 0x0f; + soutp(UART_IER, scratch); + if (scratch2 != 0 || scratch3 != 0x0f) { + /* we fail, there's nothing here */ + spin_unlock_irqrestore(&hardware_lock, flags); + pr_err("port existence test failed, cannot continue\n"); + return -ENODEV; + } + /* reset UART */ outb(0, io + UART_MCR); outb(0, io + UART_IER); @@ -285,6 +310,8 @@ static void init_hardware(void) /* turn on UART */ outb(UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2, io + UART_MCR); spin_unlock_irqrestore(&hardware_lock, flags); + + return 0; } static void drop_hardware(void) @@ -334,14 +361,19 @@ static int sir_ir_probe(struct platform_device *dev) pr_err("IRQ %d already in use.\n", irq); return retval; } + + retval = init_hardware(); + if (retval) { + del_timer_sync(&timerlist); + return retval; + } + pr_info("I/O port 0x%.4x, IRQ %d.\n", io, irq); retval = devm_rc_register_device(&sir_ir_dev->dev, rcdev); if (retval < 0) return retval; - init_hardware(); - return 0; } |