lkml.org 
[lkml]   [2019]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 4.19 024/113] tty: serial: msm_serial: avoid system lockup condition
    Hi!

    > >> [ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ]

    > > Should it use something like 5000*udelay(100), instead, as that has
    > > chance to result in closer-to-500msec wait?
    >
    > the half a second timeout didnt mean to be accurate but a worst case
    > scenario...I am not sure accuracy matters.

    Well, I'd be afraid that it would wait 5 seconds, not half a
    second. udelay(1) may be very inaccurate.

    > >> while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {
    > >> if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)
    > >> break;
    > >> udelay(1);
    > >> + if (!timeout--)
    > >> + break;
    > >> }
    > >> msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);
    > >> }
    > >
    > > Plus, should it do some kind of dev_err() to let users know that
    > > something went very wrong with their serial?
    >
    > I did consider this but then I thought that 1/2 second without
    > interrupts on the core should not go unnoticed. But I might be wrong.

    Well, maybe it will be noticed, but user will have no idea what caused
    it.

    Pavel
    --
    DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
    HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2019-08-15 09:08    [W:4.158 / U:0.200 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site