Messages in this thread | | | Date | Fri, 20 Oct 2023 10:18:55 -0400 | From | Frank Li <> | Subject | Re: [PATCH v2 Resent 6/6] i3c: master: svc: fix random hot join failure since timeout error |
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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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