Messages in this thread | | | Subject | Re: [PATCH] mtd: nand: raw: qcom_nandc: Don't clear_bam_transaction on READID | From | Sricharan Ramabadhran <> | Date | Thu, 24 Feb 2022 13:03:16 +0530 |
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Hi Konrad,
On 2/8/2022 10:15 PM, Konrad Dybcio wrote: > > On 4.02.2022 18:17, Sricharan Ramabadhran wrote: >> On 2/2/2022 12:54 PM, Sricharan Ramabadhran wrote: >>> Hi Konrad/Miquel, >>> >>> On 2/1/2022 9:21 PM, Konrad Dybcio wrote: >>>> On 01/02/2022 14:52, Miquel Raynal wrote: >>>>> Hi Konrad, >>>>> >>>>> konrad.dybcio@somainline.org wrote on Mon, 31 Jan 2022 20:54:12 +0100: >>>>> >>>>>> On 31/01/2022 15:13, Sricharan Ramabadhran wrote: >>>>>>> Hi Konrad, >>>>>>> >>>>>>> On 1/31/2022 3:39 PM, Konrad Dybcio wrote: >>>>>>>> On 28/01/2022 18:50, Sricharan Ramabadhran wrote: >>>>>>>>> Hi Konrad, >>>>>>>>> >>>>>>>>> On 1/28/2022 9:55 AM, Sricharan Ramabadhran wrote: >>>>>>>>>> Hi Miquel, >>>>>>>>>> >>>>>>>>>> On 1/26/2022 4:12 PM, Miquel Raynal wrote: >>>>>>>>>>> Hi Mani, >>>>>>>>>>> >>>>>>>>>>> mani@kernel.org wrote on Wed, 26 Jan 2022 16:03:16 +0530: >>>>>>>>>>>> On Wed, Jan 26, 2022 at 11:16:13AM +0100, Miquel Raynal wrote: >>>>>>>>>>>>> Hello, >>>>>>>>>>>>> >>>>>>>>>>>>> miquel.raynal@bootlin.com wrote on Fri, 14 Jan 2022 08:27:18 +0100: >>>>>>>>>>>>>> Hi Konrad, >>>>>>>>>>>>>> >>>>>>>>>>>>>> konrad.dybcio@somainline.org wrote on Thu, 13 Jan 2022 19:44:26 >>>>>>>> +0100: >>>>>>>>>>>>>>> While I have absolutely 0 idea why and how, running >>>>>>>>> clear_bam_transaction >>>>>>>>>>>>>>> when READID is issued makes the DMA totally clog up and refuse >>>>>>>>> to function >>>>>>>>>>>>>>> at all on mdm9607. In fact, it is so bad that all the data >>>>>>>>> gets garbled >>>>>>>>>>>>>>> and after a short while in the nand probe flow, the CPU >>>>>>>>> decides that >>>>>>>>>>>>>>> sepuku is the only option. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Removing _READID from the if condition makes it work like a >>>>>>>>> charm, I can >>>>>>>>>>>>>>> read data and mount partitions without a problem. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org> >>>>>>>>>>>>>>> --- >>>>>>>>>>>>>>> This is totally just an observation which took me an inhumane >>>>>>>>> amount of >>>>>>>>>>>>>>> debug prints to find.. perhaps there's a better reason behind >>>>>>>>> this, but >>>>>>>>>>>>>>> I can't seem to find any answers.. Therefore, this is a BIG RFC! >>>>>>>>>>>>>> I'm adding two people from codeaurora who worked a lot on this >>>>>>>> driver. >>>>>>>>>>>>>> Hopefully they will have an idea :) >>>>>>>>>>>>> Sadre, I've spent a significant amount of time reviewing your >>>>>>> patches, >>>>>>>>>>>>> now it's your turn to not take a month to answer to your peers >>>>>>>>>>>>> proposals. >>>>>>>>>>>>> >>>>>>>>>>>>> Please help reviewing this patch. >>>>>>>>>>>> Sorry. I was hoping that Qcom folks would chime in as I don't >>>>>> have any idea >>>>>>>>>>>> about the mdm9607 platform. It could be that the mail server >>>>>> migration from >>>>>>>>>>>> codeaurora to quicinc put a barrier here. >>>>>>>>>>>> >>>>>>>>>>>> Let me ping them internally. >>>>>>>>>>> Oh, ok, I didn't know. Thanks! >>>>>>>>>> Sorry Miquel, somehow we did not get this email in our inbox. >>>>>>>>>> Thanks to Mani for pinging us, we will test this up today and >>>> get back. >>>>>>>>> While we could not reproduce this issue on our ipq boards (do >>> not have a mdm9607 right now) and >>>>>>>>> issue does not look any obvious. >>>>>>>>> can you please give the debug logs that you did for the above >>> stage by stage ? >>>>>>>> I won't have access to the board for about two weeks, sorry. >>>>>>>> >>>>>>>> When I get to it, I'll surely try to send you the logs, though there >>>>>>>> >>>>>>>> wasn't much more than just something jumping to who-knows-where >>>>>>>> >>>>>>>> after clear_bam_transaction was called, resulting in values >> associated with >>>>>>>> >>>>>>>> the NAND being all zeroed out in pr_err/_debug/etc. >>>>>>>> >>>>>>> Ok sure. So was the READID command itself failing (or) the > subsequent one ? >>>>>>> We can check which parameter reset by the clear_bam_transaction is > causing the >>>>>>> failure. Meanwhile, looping in Pradeep who has access to the > board, so in a better >>>>>>> position to debug. >>>>>> I'm sorry I have so few details on hand, and no kernel tree (no access to that machine either, for now). >>>>>> >>>>>> >>>>>> I will try to describe to the best of my abilities what I recall. >>>>>> >>>>>> >>>>>> My methodology of making sure things don't go haywire was to print the oob size >>>>>> >>>>>> of our NAND basically every two lines of code (yes, i was very desperate at one point), >>>>>> >>>>>> as that was zeroed out when *the bug* happened, >>>>> This does look like a pointer error at some point and some kernel data >>>>> has been corrupted very badly by the driver. >>>>> >>>>>> leading to a kernel bug/panic/stall >>>>>> >>>>>> (can't recall what exactly it was, but it said something along the lines of "no support for >>>>>> >>>>>> oob size 0" and then it didn't fail graceully, leading to some bad jumps and ultimately >>>>>> >>>>>> a dead platform..) >>>>>> >>>>>> >>>>>> after hours of digging, I found out that everything goes fine until clear_bam_transaction is called, >>>>> Do you remember if this function was called for the first time when >>>>> this happened? >>>> I think so, if I recall correctly there are no more callers in this path, as readid is the first nand command executed in flash probe flow. >>>> >>>> >>>> >>>>>> after that gets executed every nand op starts reading all zeroes (for example in JEDEC ID check) >>>>>> >>>>>> so I added the changes from this patch, and things magically started working... My suspicion is >>>>>> >>>>>> that the underlying FIFO isn't fully drained (is it a FIFO on 9607? bah, i work on too many socs at once) >>>>> I don't see it in the list of supported devices, what's the exact >>>>> compatible used? >>>> qcom,ipq4019-nand >>>> >>>> >>>> >>>>>> and this function only makes Linux think it is, without actually draining it, and the leftover >>>>>> >>>>>> commands get executed with some parts of them getting overwritten, resulting in the >>>>>> >>>>>> famous garbage in - garbage out situation, but that's only a guesstimate.. >>>>> I would bet for a non allocated bam-ish pointer that is reset to zero >>>>> in the clear_bam_transaction() helper. >>>>> >>>>> Can you get your hands on the board again? >>>> Sure, but as I mentioned previously, only in about 2 weeks, I can't really do any dev before then.. :( >>>> >>>> >>>> >>>>> It would be nice to check if the allocation always occurs before use, >>>>> and if yes on how much bytes. >>>>> >>>>> If the pointer is not dangling, then perhaps something else smashes >>>>> that pointer. >>>> >>>> Konrad >>>> >>>>>> Do note this somehow worked fine on 5.11 and then broke on 5.12/13. I went as far as replacing most >>>>>> >>>>>> of the kernel with the updated/downgraded parts via git checkout (i tried many combinations), >>>>>> >>>>>> to no avail.. I even tried different compilers and optimization levels, thinking it could have been >>>>>> >>>>>> a codegen issue, but no luck either. >>>>>> >>>>>> >>>>>> I.. do understand this email is a total mess to read, as much as it was to write, but >>>>>> >>>>>> without access to my code and the machine itself I can't give you solid details, and >>>>>> >>>>>> the fact this situation is far from ordinary doesn't help either.. >>>>>> >>>>>> >>>>>> The latest (ancient, not quite pretty, but probably working if my memory is correct) version of my patches >>>>>> >>>>>> for the mdm9607 is available at [1], I will push the new revision after I get access to the workstation. >>>>>> >>> + few more who have access to the board. >>> >>> Going by the description, for kernel corruption, we can try out a KASAN build. >>> Since you have mentioned it worked till 5.11, you bisected the driver till 5.11 head and it worked ? >>> >> Tried running a KASAN enabled image on IPQ board, but no luck. Nothing came out. >> Only if someone with the board can help here, we can proceed >> >> >> Regards, >> Sricharan >> > I have the board with me again. Please tell me where do we start :)
Sorry for the delayed response.
As a first step, Can you enable KASAN and check if you get any warnings ?
Then, can you check inside clear_bam_transaction, which parameter resetting specifically is causing the issue ?
Regards, Sricharan
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