lkml.org 
[lkml]   [2019]   [Jan]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] dmaengine: at_xdmac: Fix wrongfull report of a channel as in use
On 21-01-19, 14:38, Codrin.Ciubotariu@microchip.com wrote:
> On 20.01.2019 13:04, Vinod Koul wrote:
> > Hi Codrin,
> >
> > On 17-01-19, 16:10, Codrin.Ciubotariu@microchip.com wrote:
> >> From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
> >>
> >> atchan->status is used for two things:
> >> - pass channel interrupts status from interrupt handler to tasklet;
> >> - channel information like whether it is cyclic or paused;
> >>
> >> Since these operations have nothing in common, this patch adds a
> >> different struct member to keep the interrupts status.
> >>
> >> Fixes a bug in which a channel is wrongfully reported as in use when
> >> trying to obtain a new descriptior for a previously used cyclic channel.
> >
> > This looks reasonable but am unable to see how the bug is fixed. Perhaps
> > would be great to split the bug part (which can go to fixes) and remove
> > the reuse of variable as a subsequent patch..
>
> Hi Vinod,
>
> This patch is the fix, since it moves the operations on atchan->status,
> in which the interrupt status register is saved, to a different member
> (irq_status). The AT_XDMAC_CHAN_IS_CYCLIC and AT_XDMAC_CHAN_IS_PAUSED
> bits have nothing in common with the interrupt status register.
>
> The bug reproduces when a device_terminate_all() is called,
> (AT_XDMAC_CHAN_IS_CYCLIC cleared on atchan->status) and then a late End
> of Block interrupt arrives (AT_XDMAC_CIS_BIS), which sets bit 0 of
> atchan->status. Bit 0 is also used for AT_XDMAC_CHAN_IS_CYCLIC, so when
> a new descriptor for a cyclic transfer is created, the driver reports
> the channel as in use:
>
> if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
> dev_err(chan2dev(chan), "channel currently used\n");
> return NULL;
> }
>
> I can send v2 if you consider the commit message misleading.

Yes please, that would be better and pls add fixes as suggested by
Ludovic along with his ack

--
~Vinod

\
 
 \ /
  Last update: 2019-01-23 13:19    [W:0.069 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site