Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1486658

Re: [PATCH 1/3] i2c: bcm2835: Fix hang for writing messages larger than 16 bytes

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

Noralf Trønnes <noralf@tronnes.org> writes:

> Writing messages larger than the FIFO size results in a hang, rendering
> the machine unusable. This is because the RXD status flag is set on the
> first interrupt which results in bcm2835_drain_rxfifo() stealing bytes
> from the buffer. The controller continues to trigger interrupts waiting
> for the missing bytes, but bcm2835_fill_txfifo() has none to give.
> In this situation wait_for_completion_timeout() apparently is unable to
> stop the madness.
>
> The BCM2835 ARM Peripherals datasheet has this to say about the flags:
>   TXD: is set when the FIFO has space for at least one byte of data.
>   RXD: is set when the FIFO contains at least one byte of data.
>   TXW: is set during a write transfer and the FIFO is less than full.
>   RXR: is set during a read transfer and the FIFO is or more full.
>
> Implementing the logic from the downstream i2c-bcm2708 driver solved
> the hang problem.
>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>

Patches 1, 3 are:

Reviewed-by: Eric Anholt <eric@anholt.net>

For patch 2 I followed some of it, but couldn't quite say it's a review.
I trust your testing, and that the path has had a lot more testing in
the downstream tree, so it's:

Acked-by: Eric Anholt <eric@anholt.net>

Thanks!

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 1/3] i2c: bcm2835: Fix hang for writing messages larger than 16 bytes Noralf Trønnes <noralf@tronnes.org> - 2016-09-19 17:30 +0200
  [PATCH 3/3] i2c: bcm2835: Use ratelimited logging on transfer errors Noralf Trønnes <noralf@tronnes.org> - 2016-09-19 17:30 +0200
  [PATCH 2/3] i2c: bcm2835: Add support for combined write-read transfer Noralf Trønnes <noralf@tronnes.org> - 2016-09-19 17:30 +0200
    Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read  transfer Martin Sperl <kernel@martin.sperl.org> - 2016-09-20 09:20 +0200
      Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read  transfer Noralf Trønnes <noralf@tronnes.org> - 2016-09-20 10:50 +0200
        Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read  transfer Martin Sperl <kernel@martin.sperl.org> - 2016-09-20 12:20 +0200
          Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read  transfer Noralf Trønnes <noralf@tronnes.org> - 2016-09-20 13:00 +0200
            Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read transfer kernel@martin.sperl.org - 2016-09-20 13:30 +0200
              Re: [PATCH 2/3] i2c: bcm2835: Add support for combined write-read  transfer Noralf Trønnes <noralf@tronnes.org> - 2016-09-21 15:50 +0200
  Re: [PATCH 1/3] i2c: bcm2835: Fix hang for writing messages larger than 16 bytes Eric Anholt <eric@anholt.net> - 2016-09-19 19:00 +0200
    Re: [PATCH 1/3] i2c: bcm2835: Fix hang for writing messages larger  than 16 bytes Noralf Trønnes <noralf@tronnes.org> - 2016-09-19 19:40 +0200
  Re: [PATCH 1/3] i2c: bcm2835: Fix hang for writing messages larger  than 16 bytes Martin Sperl <kernel@martin.sperl.org> - 2016-09-20 09:50 +0200

csiph-web