Re: [PATCH 3/3] mtd: rawnand: marvell: add suspend and resume hooks

[Boris Brezillon <boris.brezillon@bootlin.com>]

Hi Daniel,

On Sat, 7 Jul 2018 00:26:22 +0200
Daniel Mack <daniel@zonque.org> wrote:

> On Saturday, July 07, 2018 12:15 AM, Daniel Mack wrote:
> > Hi,
> > 
> > On 07/06/2018 11:22 PM, Boris Brezillon wrote:  
> >> On Fri,  6 Jul 2018 22:14:15 +0200
> >> Daniel Mack <daniel@zonque.org> wrote:
> >>  
> >>> This patch restores the suspend and resume hooks that the old driver used
> >>> to have. Apart from stopping and starting the clocks, the resume callback
> >>> also nullifies the selected_chip pointer, so the next command that is issued
> >>> will re-select the chip and thereby restore the timing registers.
> >>>
> >>> Without this patch, a PXA3xx based system would cough up an error similar to
> >>> the one below after resume.
> >>>
> >>> [   44.660162] marvell-nfc 43100000.nand-controller: Timeout waiting for  RB signal
> >>> [   44.671492] ubi0 error: ubi_io_write: error -110 while writing 2048 bytes to PEB 102:38912, written 0 bytes
> >>> [   44.682887] CPU: 0 PID: 1417 Comm: remote-control Not tainted 4.18.0-rc2+ #344
> >>> [   44.691197] Hardware name: Marvell PXA3xx (Device Tree Support)
> >>> [   44.697111] Backtrace:
> >>> [   44.699593] [<c0106458>] (dump_backtrace) from [<c0106718>] (show_stack+0x18/0x1c)
> >>> [   44.708931]  r7:00000800 r6:00009800 r5:00000066 r4:c6139000
> >>> [   44.715833] [<c0106700>] (show_stack) from [<c0678a60>] (dump_stack+0x20/0x28)
> >>> [   44.724206] [<c0678a40>] (dump_stack) from [<c0456cbc>] (ubi_io_write+0x3d4/0x630)
> >>> [   44.732925] [<c04568e8>] (ubi_io_write) from [<c0454428>] (ubi_eba_write_leb+0x690/0x6fc)
> >>> ...
> >>>
> >>> Signed-off-by: Daniel Mack <daniel@zonque.org>  
> >>
> >> You probably want patch 2 and 3 backported to stable.  
> > 
> > Given that nobody has cared so far and the only board that depends on
> > proper PM that seems to be using this driver has bitrot quite badly in
> > the past and is undergoing a major rewrite currently, I'm not sure
> > whether it's worth it really.  
> 
> Ah, I only see this now, but patch 2 also fixes a problem with the 
> .remove() callback of this driver which also blindly grabs ->reg_clk 
> without further checks.

Nope, because the clk framework checks for both ERR and NULL (see
[1]). I'm definitely not arguing that patch 2 is not needed (actually I
pushed for this solution when Greg initially added these new clks [2]),
just that it should not be flagged as stable.

> 
> Hence the entire series actually qualifies for stable@ I figure?

I'd really prefer to have a single patch go into stable. Patch 1 is
clearly not a bug fix, and patch 2 is just a dependency of patch 3, so
let's remove this dependency by either squashing both patches into a
single one or by reordering the changes.

Regards,

Boris

[1]https://elixir.bootlin.com/linux/v4.18-rc3/source/drivers/clk/clk.c#L858
[2]https://www.spinics.net/lists/arm-kernel/msg639312.html