On Wed, 8 Jun 2022, Nuno Gonçalves wrote:
> On Fri, Apr 29, 2022 at 12:24 PM Ilpo Järvinen
> <ilpo.jarvinen@xxxxxxxxxxxxxxx> wrote:
> >
> > The driver must provide throttle and unthrottle in uart_ops when it
> > sets UPSTAT_AUTORTS. Add them using existing stop_rx &
> > enable_interrupts functions.
> >
> > Compile tested (w/o linking).
> >
> > Reported-by: Nuno Gonçalves <nunojpg@xxxxxxxxx>
> > Fixes: 2a76fa283098 (serial: pl011: Adopt generic flag to store auto
> > RTS status)
> > Cc: Lukas Wunner <lukas@xxxxxxxxx>
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> >
> > ---
> >
> > Maybe this one is the correct solution (I'm not able to test on the real
> > hw though)?
>
> I still get a crash with your patch:
>
> [ 827.145500] Unable to handle kernel NULL pointer dereference at
> virtual address 0000000000000000
> [ 827.154515] Mem abort info:
> [ 827.157394] ESR = 0x86000005
> [ 827.160538] EC = 0x21: IABT (current EL), IL = 32 bits
> [ 827.165979] SET = 0, FnV = 0
> [ 827.169115] EA = 0, S1PTW = 0
> [ 827.172332] FSC = 0x05: level 1 translation fault
> [ 827.177320] user pgtable: 4k pages, 39-bit VAs, pgdp=00000000043f2000
> [ 827.183900] [0000000000000000] pgd=0000000000000000,
> p4d=0000000000000000, pud=0000000000000000
> [ 827.192815] Internal error: Oops: 86000005 [#1] PREEMPT SMP
> [ 827.198488] CPU: 2 PID: 372 Comm: kworker/u8:0 Tainted: G W
> 5.18.2 #1
> [ 827.206356] Hardware name: Raspberry Pi Compute Module 3 Plus Rev 1.0 (DT)
> [ 827.213339] Workqueue: events_unbound flush_to_ldisc
> [ 827.218407] pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 827.225481] pc : 0x0
> [ 827.227701] lr : uart_throttle+0x94/0x160
Hi Nuno,
It seems I managed to put the .throttle and .unthrottle into the wrong
ops within amba-pl011.c. I'm sorry about the extra trouble. This patch has
a bit higher likelihood of doing something useful to the problem:
From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
[PATCH v3] serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle
The driver must provide throttle and unthrottle in uart_ops when it
sets UPSTAT_AUTORTS. Add them using existing stop_rx &
enable_interrupts functions.
Reported-by: Nuno Gonçalves <nunojpg@xxxxxxxxx>
Fixes: 2a76fa283098 (serial: pl011: Adopt generic flag to store auto RTS status)
Cc: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 97ef41cb2721..16a21422ddce 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1367,6 +1367,15 @@ static void pl011_stop_rx(struct uart_port *port)
pl011_dma_rx_stop(uap);
}
+static void pl011_throttle_rx(struct uart_port *port)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ pl011_stop_rx(port);
+ spin_unlock_irqrestore(&port->lock, flags);
+}
+
static void pl011_enable_ms(struct uart_port *port)
{
struct uart_amba_port *uap =
@@ -1788,9 +1797,10 @@ static int pl011_allocate_irq(struct uart_amba_port *uap)
*/
static void pl011_enable_interrupts(struct uart_amba_port *uap)
{
+ unsigned long flags;
unsigned int i;
- spin_lock_irq(&uap->port.lock);
+ spin_lock_irqsave(&uap->port.lock, flags);
/* Clear out any spuriously appearing RX interrupts */
pl011_write(UART011_RTIS | UART011_RXIS, uap, REG_ICR);
@@ -1812,7 +1822,14 @@ static void pl011_enable_interrupts(struct uart_amba_port *uap)
if (!pl011_dma_rx_running(uap))
uap->im |= UART011_RXIM;
pl011_write(uap->im, uap, REG_IMSC);
- spin_unlock_irq(&uap->port.lock);
+ spin_unlock_irqrestore(&uap->port.lock, flags);
+}
+
+static void pl011_unthrottle_rx(struct uart_port *port)
+{
+ struct uart_amba_port *uap = container_of(port, struct uart_amba_port, port);
+
+ pl011_enable_interrupts(uap);
}
static int pl011_startup(struct uart_port *port)
@@ -2225,6 +2242,8 @@ static const struct uart_ops amba_pl011_pops = {
.stop_tx = pl011_stop_tx,
.start_tx = pl011_start_tx,
.stop_rx = pl011_stop_rx,
+ .throttle = pl011_throttle_rx,
+ .unthrottle = pl011_unthrottle_rx,
.enable_ms = pl011_enable_ms,
.break_ctl = pl011_break_ctl,
.startup = pl011_startup,
--
tg: (f2906aa86338..) pl011/add-throttle (depends on: tty-next)
