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Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA

From Arnd Bergmann <arnd@arndb.de>
Newsgroups linux.kernel
Subject Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA
Date 2015-10-06 11:40 +0200
Message-ID <qgwT0-2d0-19@gated-at.bofh.it> (permalink)
References <qgcUh-73G-3@gated-at.bofh.it> <qgcUh-73G-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Monday 05 October 2015 13:10:07 Jon Hunter wrote:
> Add support for the Tegra210 Audio DMA controller that is used for
> transferring data between system memory and the Audio sub-system.
> The driver only supports cyclic transfers because this is being solely
> used for audio.
> 
> This driver is based upon the work by Dara Ramesh <dramesh@nvidia.com>.
> 
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>

This version looks much better!

Just one small comment:

> +	slave_req = dma_spec->args[0];
> +	slave_dir = dma_spec->args[1];
> +
> +	if (slave_req == 0)
> +		return NULL;
> +
> +	switch (slave_dir) {
> +	case ADMA_AHUB_TO_MEM:
> +		if (slave_req > tdma->rx_requests)
> +			return NULL;
> +
> +		if (tdma->rx_requests_reserved & BIT(slave_req))
> +			return NULL;
> +
> +		tdma->rx_requests_reserved |= BIT(slave_req);
> +		break;

The rx_requests_reserved logic looks racy, if you have more than
one concurrent request or release. Better use atomic_test_and_set()
here and turn the variable into an atomic_t.

	Arbd
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[PATCH V2 0/2] Add support for Tegra210 ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-05 14:20 +0200
  [PATCH V2 1/2] Documentation: DT: Add binding documentation for NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-05 14:20 +0200
    Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Mark Rutland <mark.rutland@arm.com> - 2015-10-05 15:20 +0200
      Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-06 11:20 +0200
        Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-07 01:00 +0200
          Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-07 17:30 +0200
            Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-07 18:10 +0200
              Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Mark Rutland <mark.rutland@arm.com> - 2015-10-07 18:40 +0200
    Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-07 01:10 +0200
      Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-07 10:50 +0200
        Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-07 18:10 +0200
          Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-07 18:30 +0200
            Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-07 21:40 +0200
              Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-08 12:00 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-08 16:30 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-09 12:30 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-09 17:30 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-12 16:00 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Stephen Warren <swarren@wwwdotorg.org> - 2015-10-12 20:00 +0200
                Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-13 15:00 +0200
        Re: [PATCH V2 1/2] Documentation: DT: Add binding documentation for  NVIDIA ADMA Mark Rutland <mark.rutland@arm.com> - 2015-10-07 18:40 +0200
  [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-05 14:20 +0200
    Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210 ADMA Arnd Bergmann <arnd@arndb.de> - 2015-10-06 11:40 +0200
      Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210  ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-06 11:50 +0200
    Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210  ADMA Vinod Koul <vinod.koul@intel.com> - 2015-10-14 13:30 +0200
      Re: [PATCH V2 2/2] dmaengine: tegra-adma: Add support for Tegra210  ADMA Jon Hunter <jonathanh@nvidia.com> - 2015-10-14 15:40 +0200

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