[PATCH V6 4/4] MTD: pxa3xx_nand: enhance suspend and resume routine

[Daniel Mack]

On Tue, Jul 12, 2011 at 5:56 PM, Igor Grinberg <grinberg at compulab.co.il> wrote:
> On 07/12/11 15:02, Daniel Mack wrote:
>
>> On Tue, Jul 12, 2011 at 1:39 PM, Daniel Mack <zonque at gmail.com> wrote:
>>> On Tue, Jul 12, 2011 at 12:28 PM, Lei Wen <leiwen at marvell.com> wrote:
>>>> This patch add protection on the suspend&resume path to prevent
>>>> some unexpected behavior, like interrupt occur at the very second
>>>> of resume back and it don't follow normal command path, which lead
>>>> to bug.
>>>>
>>>> Signed-off-by: Lei Wen <leiwen at marvell.com>
>>>> ---
>>>>  drivers/mtd/nand/pxa3xx_nand.c |   28 ++++++++++++++++++++++++++++
>>>>  1 files changed, 28 insertions(+), 0 deletions(-)
>>>>
>>> [...]
>>>
>>>> @@ -1267,6 +1283,18 @@ static int pxa3xx_nand_resume(struct platform_device *pdev)
>>>>        info->cs = 0xff;
>>>>        clk_enable(info->clk);
>>>>
>>>> +       /*
>>>> +        * As the spec, the NDSR would be updated to 0x1800 when
>>>> +        * do the nand_clk disable/enable.
>>>> +        * To prevent it damage state machine of the driver, clear
>>>> +        * all status before resume
>>>> +        */
>>>> +       nand_writel(nand, NDSR, NDSR_MASK);
>>> This doesn't build:
>>>
>>>  CC      drivers/mtd/nand/pxa3xx_nand.o
>>> drivers/mtd/nand/pxa3xx_nand.c: In function 'pxa3xx_nand_resume':
>>> drivers/mtd/nand/pxa3xx_nand.c:1292: error: 'nand' undeclared (first
>>> use in this function)
>>> drivers/mtd/nand/pxa3xx_nand.c:1292: error: (Each undeclared
>>> identifier is reported only once
>>> drivers/mtd/nand/pxa3xx_nand.c:1292: error: for each function it appears in.)
>>> drivers/mtd/nand/pxa3xx_nand.c:1294: error: 'mtd' undeclared (first
>>> use in this function)
>>> make[3]: *** [drivers/mtd/nand/pxa3xx_nand.o] Error 1
>>>
>>> I guess this was not even compile tested? Anyway, I did a trivial
>>> fix-up and will test.
>> Also, with this (fixed) patch applied, the system doesn't resume at
>> all. No messages, it simply doesn't come back.
>
> I was skeptic about the clock being disabled in Lei's patch,
> as I observed system hangs if that clock was disabled back then in 2.6.31,
> but wanted to give it a try, because things has changed since then.
>
> Now I see, that Lei already sent v7 without clock toggling...

Yes, we debugged this quickly via Jabber, and without the clock
disable, things work fine for me again.

Daniel