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    SubjectRe: [PATCH v2 Resent 6/6] i3c: master: svc: fix random hot join failure since timeout error
    On Fri, Oct 20, 2023 at 04:06:45PM +0200, Miquel Raynal wrote:
    > Hi Frank,
    >
    > Frank.li@nxp.com wrote on Thu, 19 Oct 2023 11:39:42 -0400:
    >
    > > On Thu, Oct 19, 2023 at 08:44:52AM +0200, Miquel Raynal wrote:
    > > > Hi Frank,
    > > >
    > > > Frank.Li@nxp.com wrote on Wed, 18 Oct 2023 11:59:26 -0400:
    > > >
    > > > > master side report:
    > > > > silvaco-i3c-master 44330000.i3c-master: Error condition: MSTATUS 0x020090c7, MERRWARN 0x00100000
    > > > >
    > > > > BIT 20: TIMEOUT error
    > > > > The module has stalled too long in a frame. This happens when:
    > > > > - The TX FIFO or RX FIFO is not handled and the bus is stuck in the
    > > > > middle of a message,
    > > > > - No STOP was issued and between messages,
    > > > > - IBI manual is used and no decision was made.
    > > >
    > > > I am still not convinced this should be ignored in all cases.
    > > >
    > > > Case 1 is a problem because the hardware failed somehow.
    > >
    > > But so far, no action to handle this case in current code.
    >
    > Yes, but if you detect an issue and ignore it, it's not better than
    > reporting it without handling it. Instead of totally ignoring this I
    > would at least write a debug message (identical to what's below) before
    > returning false, even though I am not convinced unconditionally
    > returning false here is wise. If you fail a hardware sequence because
    > you added a printk, it's a problem. Maybe you consider this line as
    > noise, but I believe it's still an error condition. Maybe, however,
    > this bit gets set after the whole sequence, and this is just a "bus
    > is idle" condition. If that's the case, then you need some
    > additional heuristics to properly ignore the bit?
    >

    dev_err(master->dev,
    "Error condition: MSTATUS 0x%08x, MERRWARN 0x%08x\n",
    mstatus, merrwarn);
    +
    + /* ignore timeout error */
    + if (merrwarn & SVC_I3C_MERRWARN_TIMEOUT)
    + return false;
    +

    Is it okay move SVC_I3C_MERRWARN_TIMEOUT after dev_err?

    Frank


    > > In svc_i3c_master_xfer() have not check this flags. also have not enable
    > > ERRWARN irq.
    > >
    > > If we met this case, we can add new functions/argument to handle this.
    > > Then we can real debug the code and recover bus.
    > >
    > > Without this patch, simplest add some debug message before issue
    > > SVC_I3C_MCTRL_REQUEST_AUTO_IBI, TIMEOUT will be set.
    >
    > Yes, and sometimes it won't be an issue, but sometimes it may. Maybe we
    > can find more advanced heuristics there.
    >
    > > And svc_i3c_master_error() was only called by svc_i3c_master_ibi_work().
    > >
    > > So I can think only case 3 happen in svc_i3c_master_ibi_work().
    >
    > Case 3 cannot be handled by Linux (because of the natural latency of
    > the OS).
    >
    > >
    > > Frank
    > >
    > > > Case 2 is fine I guess.
    > > > Case 3 is not possible in Linux, this will not be supported.
    > > >
    > > > > The maximum stall period is 10 KHz or 100 μs.
    > > >
    > > > s/10 KHz//
    > > >
    > > > >
    > > > > This is a just warning. System irq thread schedule latency is possible
    > > > > bigger than 100us. Just omit this waring.
    > > >
    > > > This can be considered as being just a warning as the system IRQ
    > > > latency can easily be greater than 100us.
    >
    > This was skipped in your v3.
    >
    > > > > Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
    > > > > Cc: stable@vger.kernel.org
    > > > > Signed-off-by: Frank Li <Frank.Li@nxp.com>
    > > > > ---
    >
    > Thanks,
    > Miquèl

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