linux-kernel - Re: [PATCH v1 5/5] ASoC: tegra: ahub: Reset hardware properly

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Date:   Fri, 15 Jan 2021 16:02:50 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Sameer Pujar <spujar@...dia.com>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Takashi Iwai <tiwai@...e.com>, Jaroslav Kysela <perex@...ex.cz>
Cc:     alsa-devel@...a-project.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 5/5] ASoC: tegra: ahub: Reset hardware properly

12.01.2021 15:58, Dmitry Osipenko пишет:
> Assert hardware reset before clocks are enabled and then de-assert it
> after clocks are enabled. This brings hardware into a predictable state
> and removes relying on implicit de-assertion of resets which is done by
> the clk driver.
> 
> Tested-by: Peter Geis <pgwipeout@...il.com>
> Tested-by: Nicolas Chauvet <kwizart@...il.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  sound/soc/tegra/tegra30_ahub.c | 33 ++++++++++++++++-----------------
>  sound/soc/tegra/tegra30_ahub.h |  1 +
>  2 files changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/sound/soc/tegra/tegra30_ahub.c b/sound/soc/tegra/tegra30_ahub.c
> index 4dbb58f7ea36..246cf6a373a1 100644
> --- a/sound/soc/tegra/tegra30_ahub.c
> +++ b/sound/soc/tegra/tegra30_ahub.c
> @@ -65,10 +65,20 @@ static int tegra30_ahub_runtime_resume(struct device *dev)
>  {
>  	int ret;
>  
> +	ret = reset_control_assert(ahub->reset);
> +	if (ret)
> +		return ret;
> +
>  	ret = clk_bulk_prepare_enable(ahub->nclocks, ahub->clocks);
>  	if (ret)
>  		return ret;
>  
> +	ret = reset_control_reset(ahub->reset);
> +	if (ret) {
> +		clk_bulk_disable_unprepare(ahub->nclocks, ahub->clocks);
> +		return ret;
> +	}
> +
>  	regcache_cache_only(ahub->regmap_apbif, false);
>  	regcache_cache_only(ahub->regmap_ahub, false);

I just realized that this is incorrect version of the patch which misses
the regcache syncing after the h/w reset. I'll make a v2.