lkml.org 
[lkml]   [2019]   [Feb]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 1/5] i2c:ocores: stop transfer on timeout
On Mon, Feb 11, 2019 at 09:31:18AM +0100, Federico Vaga wrote:
> Detecting a timeout is ok, but we also need to assert a STOP command on
> the bus in order to prevent it from generating interrupts when there are
> no on going transfers.
>
> Example: very long transmission.
>
> 1. ocores_xfer: START a transfer
> 2. ocores_isr : handle byte by byte the transfer
> 3. ocores_xfer: goes in timeout [[bugfix here]]
> 4. ocores_xfer: return to I2C subsystem and to the I2C driver
> 5. I2C driver : it may clean up the i2c_msg memory
> 6. ocores_isr : receives another interrupt (pending bytes to be
> transferred) but the i2c_msg memory is invalid now
>
> So, since the transfer was too long, we have to detect the timeout and
> STOP the transfer.
>
> Another point is that we have a critical region here. When handling the
> timeout condition we may have a running IRQ handler. For this reason I
> introduce a spinlock.
>
> In order to make easier to understan locking I have:
> - added a new function to handle timeout
> - modified the current ocores_process() function in order to be protected
> by the new spinlock
> Like this it is obvious at first sight that this locking serializes
> the execution of ocores_process() and ocores_process_timeout()
>
> Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
>

Applied to for-next, thanks!

[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2019-02-11 11:25    [W:0.124 / U:2.452 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site