On 12/20/2012 01:10 PM, Lucas Stach wrote:

Am Donnerstag, den 20.12.2012, 12:44 -0700 schrieb Stephen Warren:

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On 12/19/2012 04:17 PM, Lucas Stach wrote:

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This adds the driver for the Tegra 2x AC97 host controller.

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+static void tegra20_ac97_codec_warm_reset(struct snd_ac97 *ac97) +{

• u32 readback;
• unsigned long timeout;
• /*

• * although sync line is driven by the DAC pad group warm reset using
  

• * the controller cmd is not working, have to toggle sync line
  

• * manually.
  

• */
  

• gpio_request(workdata->sync_gpio, "codec-sync");

Hmm. There's an AC'97 command to reset the CODEC and we don't implement it? Uggh.

As far as I could figure from the downstream register doc there is a command implemented in the host controller that's supposed to do the warm reset, but in my testing it didn't work. Sadly I have not received any documentation about the host controller from NVIDIA up until now, so I don't now if we could make this work somehow. Bug Submission ID#: 196075

What system was that bug submitted into? It's not a regular NVIDIA internal bug number. I'll see who I can ask about this feature...

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• ac97->sync_gpio = of_get_named_gpio(pdev->dev.of_node,

• 			    "nvidia,codec-sync-gpio", 0);
  

• if (!gpio_is_valid(ac97->sync_gpio)) {

• dev_err(&pdev->dev, "no codec-sync GPIO supplied\n");
  

• goto err_clk_put;
  

• }

I don't know what this is, so I'll ask if it's strictly required too.

Until we manage to get the host controller warm reset command working this is fixed to be the _FS line of the DAP connected to the codec, so strictly required.

I'd like to investigate whether the warm reset command can be made to work before actually committing to a DT binding that requires this GPIO to be specified; the DT binding is supposed to be basically static.