Re: [PATCH 1/3] serial: qcom-geni: fix hard lockup on buffer flush

[Doug Anderson]

Hi,

On Tue, Jun 25, 2024 at 7:53 AM Johan Hovold <johan@xxxxxxxxxx> wrote:
>
> On Mon, Jun 24, 2024 at 01:45:17PM -0700, Doug Anderson wrote:
>
> > Also: if we're looking at quick/easy to land and just fix the hard
> > lockup, I'd vote for this (I can send a real patch, though I'm about
> > to go on vacation):
> >
> > --
> >
> > @@ -904,8 +904,8 @@ static void qcom_geni_serial_handle_tx_fifo(struct
> > uart_port *uport,
> >                 goto out_write_wakeup;
> >
> >         if (!port->tx_remaining) {
> > -               qcom_geni_serial_setup_tx(uport, pending);
> > -               port->tx_remaining = pending;
> > +               port->tx_remaining = min(avail, pending);
> > +               qcom_geni_serial_setup_tx(uport, port->tx_remaining);
> >
> >                 irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN);
> >                 if (!(irq_en & M_TX_FIFO_WATERMARK_EN))
> >
> > --
> >
> > That will fix the hard lockup, is short and sweet, and also doesn't
> > end up outputting NUL bytes.
>
> Yeah, this might be a good stop gap even if performance suffers.

I've officially posted this as:

https://lore.kernel.org/r/20240625092440.1.Icf914852be911b95aefa9d798b6f1cd1a180f985@changeid

I realized that I didn't need to re-calculate "chunk" so the patch is
very slightly different than I posted above but should be effectively
the same.

-Doug