linux-kernel - Re: [PATCH 5/7] soundwire: intel: follow documentation sequences for SHIM registers

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Message-ID: <20200320135145.GE4885@vkoul-mobl>
Date:   Fri, 20 Mar 2020 19:21:45 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Rander Wang <rander.wang@...el.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH 5/7] soundwire: intel: follow documentation sequences for
 SHIM registers

On 11-03-20, 17:10, Pierre-Louis Bossart wrote:
> From: Rander Wang <rander.wang@...el.com>
> 
> Somehow the existing code is not aligned with the steps described in
> the documentation, refactor code and make sure the register

Is the documentation available public space so that we can correct

> programming sequences are correct.
> 
> This includes making sure SHIM_SYNC is programmed only once, before
> the first link is powered on.
> 
> Note that the SYNCPRD value is tied only to the XTAL value and not the
> current bus frequency or the frame rate.
> 
> Signed-off-by: Rander Wang <rander.wang@...el.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/intel.c | 186 ++++++++++++++++++++++++++++----------
>  1 file changed, 139 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> index 3c271a8044b8..9c6514fe1284 100644
> --- a/drivers/soundwire/intel.c
> +++ b/drivers/soundwire/intel.c
> @@ -46,7 +46,8 @@
>  #define SDW_SHIM_LCTL_SPA		BIT(0)
>  #define SDW_SHIM_LCTL_CPA		BIT(8)
>  
> -#define SDW_SHIM_SYNC_SYNCPRD_VAL	0x176F
> +#define SDW_SHIM_SYNC_SYNCPRD_VAL_24	(24000 / SDW_CADENCE_GSYNC_KHZ - 1)
> +#define SDW_SHIM_SYNC_SYNCPRD_VAL_38_4	(38400 / SDW_CADENCE_GSYNC_KHZ - 1)
>  #define SDW_SHIM_SYNC_SYNCPRD		GENMASK(14, 0)
>  #define SDW_SHIM_SYNC_SYNCCPU		BIT(15)
>  #define SDW_SHIM_SYNC_CMDSYNC_MASK	GENMASK(19, 16)
> @@ -283,11 +284,48 @@ static int intel_link_power_up(struct sdw_intel *sdw)
>  {
>  	unsigned int link_id = sdw->instance;
>  	void __iomem *shim = sdw->link_res->shim;
> +	u32 *shim_mask = sdw->link_res->shim_mask;

this is a local pointer, so the one defined previously is not used.

> +	struct sdw_bus *bus = &sdw->cdns.bus;
> +	struct sdw_master_prop *prop = &bus->prop;
>  	int spa_mask, cpa_mask;
> -	int link_control, ret;
> +	int link_control;
> +	int ret = 0;
> +	u32 syncprd;
> +	u32 sync_reg;
>  
>  	mutex_lock(sdw->link_res->shim_lock);
>  
> +	/*
> +	 * The hardware relies on an internal counter,
> +	 * typically 4kHz, to generate the SoundWire SSP -
> +	 * which defines a 'safe' synchronization point
> +	 * between commands and audio transport and allows for
> +	 * multi link synchronization. The SYNCPRD value is
> +	 * only dependent on the oscillator clock provided to
> +	 * the IP, so adjust based on _DSD properties reported
> +	 * in DSDT tables. The values reported are based on
> +	 * either 24MHz (CNL/CML) or 38.4 MHz (ICL/TGL+).

Sorry this looks quite bad to read, we have 80 chars, so please use
like below:

	/*
         * The hardware relies on an internal counter, typically 4kHz,
         * to generate the SoundWire SSP - which defines a 'safe'
         * synchronization point between commands and audio transport
         * and allows for multi link synchronization. The SYNCPRD value
         * is only dependent on the oscillator clock provided to
         * the IP, so adjust based on _DSD properties reported in DSDT
         * tables. The values reported are based on either 24MHz
         * (CNL/CML) or 38.4 MHz (ICL/TGL+).
	 */

-- 
~Vinod