Re: GPMI-NAND Status?

From: Huang Shijie <b32955@freescale.com>
To: Wolfram Sang <w.sang@pengutronix.de>
Cc: "Koen Beel" <koen.beel.barco@gmail.com>,
	"Shawn Guo" <shawn.guo@linaro.org>,
	linux-mtd@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	"Lothar Waßmann" <LW@KARO-electronics.de>
Subject: Re: GPMI-NAND Status?
Date: Tue, 9 Aug 2011 18:54:43 +0800	[thread overview]
Message-ID: <4E4111F3.5070409@freescale.com> (raw)
In-Reply-To: <20110809093546.GB1923@pengutronix.de>

Hi,
>>> DMA timeouts [1]
>>> ================
>>>
>>> [    2.560000] [ start_dma_without_bch_irq : 392 ] DMA timeout, last DMA :1
>>> [    3.560000] [ start_dma_with_bch_irq : 427 ] bch timeout!!!
>>>
>>> Always reproducible by me when trying to format mtd0. Sometimes(always?) seen
>>> by Koen during boot (on read?). Never seen by Huang? It is currently unclear if
>> After I used a different .config, it never appears in my side.
> So, you have a config which triggers this? That should be useful for
> debugging. What do you need to enable to see this?
>
My old config is made by myself. I think it was a wrong config,
and it had too much difference from the config made by 'make mxs_defconfig".

So i think it's has no use for debugging.

>> Please test the driver again when you back to office.
>> Pay attention to your version of /arch/arm/configs/mxs_defconfig.
>> Your mxs_defconfig may miss Shawn Guo's patches.
> I have all the correct patches, I triple-checked that. Regarding the
> config, I am not looking for a config that works, I want my config to
> work. I meanwhile have the feeling this is a bug in the DMA driver
> (because Aisheng Dong has DMA problems, too, in the audio path), still
> we need to be sure.
>
it's not a DMA bug, I discuss with Koen, and make sure that the bug is
caused by the GPMI or BCH.

it's a different bug from  Aisheng Dong's bug.

>>> problem overwriting all-0xff data in NAND [2]
>>> =============================================
>>>
>>> Although it occured only when writing JFFS2 images so far, this is a generic
>>> issue and needs to be fixed, right?
>>>
>> Artem said it should not change the driver, but the upper layer(jffs2).
>>
>> So I think i do not need to change the driver.
> OK, read it again, got it now. Agreed.
>
>
>>> * custom sysfs-entries
>> My sysfs-entries is in the GPMI-NAND directory.
>> Does be a mainline driver means I should not have any sysfs-entries?
>> If it does, i can remove it.
> It is some kund of ABI, so we would have to support them forever. If
> there is no really strong reason to have them, it is better to remove
> them.
>
ok, thanks.
>>> * custom kernel command line parameters
>> The kernel command line 'gpmi_nand' is to avoid the conflict with
>> other modules such as
>> SD.
>>
>> If it's be removed, I have to use different config to resolve the
>> issue which is not better either. :(
> This is a board-specific issue, so you should handle this at
> board-level, not at driver level.
>
I wish to handle it at the board level.

But I have no idea how to solve the conflict between GPMI and SD.  :(

Could you give me some hint?
thanks

>>> * namespacing (some functions have no prefix, some have "mil_", some have mx23)
>>>    (I think 'mil' means 'mtd interface layer', but why is that needed?)
>> The mil is used to make the gpmi_nand_data{} simple.
>> Without it, the gpmi_nand_data{} will very big.
>>
>> The functions which have mx23 prefix are only used in mx23.
>> The functions which have no prefix can used in both mx28 and mx23.
> I understood this, but wonder if mx23_* specific stuff has to be in the
> main driver. Will have a closer look to the driver this week, then I can
> say more.
>
thanks
>>> Complexity
>>> ==========
>>>
>>> The driver is not easy to review. I wonder if it makes sense to use incremental
>>> patches for it? maybe making it a staging driver could be a solution for that?
>> Frankly speaking, the current driver is maybe the smallest version now.
>>
>> I even do not add the on-chip BBT feature now.
> OK.
>
>>> Huang, are you interested in accepting patches or do you prefer we just point
>>> at certain code and you then fix it? Starting with a simpler driver and then
>> Feel free to mail me the patch. it's welcome.
> We'd need a branch somewhere for that, so we have a history.
>
ok.
I will try to find some solution.
>>> adding stuff might be another option if we can't chase all the bugs in the
>>> current driver.
>>>
>>> That being said, I'd think fixing the DMA issue has prio #1 and maybe we can
>>> meet in IRC or something to work that out? Is there interest in that?
>> What about gtalk?
> Definately not my favourite, but seems like Koen and you already use it.
> Might try it...
I can use the IRC too.

Huang Shijie

> Regards,
>
>      Wolfram
>