linux-kernel - Re: [PATCH] soundwire: intel: Make DEV_NUM_IDA

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Message-ID: <cfb75ee6-f290-4f59-df3b-9acea986357f@linux.intel.com>
Date:   Mon, 8 May 2023 08:59:39 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Richard Fitzgerald <rf@...nsource.cirrus.com>, vkoul@...nel.org
Cc:     yung-chuan.liao@...ux.intel.com, sanyog.r.kale@...el.com,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        patches@...nsource.cirrus.com
Subject: Re: [PATCH] soundwire: intel: Make DEV_NUM_IDA_MIN a module param



On 5/8/23 05:39, Richard Fitzgerald wrote:
> Add a module param so that globally-unique peripheral ID
> allocation is only enabled if wanted.
> 
> The globally-unique IDs were introduced by
> commit c60561014257
> ("soundwire: bus: allow device number to be unique at system level")
> 
> and
> commit 1f2dcf3a154a ("soundwire: intel: set dev_num_ida_min")
> 
> Assigning globally-unique IDs limits the total number of
> peripherals in a system, and the above two commits limit to a
> maximum of 8 peripherals. We now have hardware with more than
> 8 peripherals in total, so this limit is a problem. As the
> original commit says that it is only for debug it can be made
> optional.
I think it's a misunderstanding, the introduction of these IDs was
related to hardware programming sequences, not just debug.

I'll talk to Richard on this, please do not apply this patch for now.

> Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
> ---
>  drivers/soundwire/intel_auxdevice.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soundwire/intel_auxdevice.c b/drivers/soundwire/intel_auxdevice.c
> index b21e86084f7b..9ebbf652e47a 100644
> --- a/drivers/soundwire/intel_auxdevice.c
> +++ b/drivers/soundwire/intel_auxdevice.c
> @@ -23,8 +23,13 @@
>  #include "intel.h"
>  #include "intel_auxdevice.h"
>  
> -/* IDA min selected to avoid conflicts with HDaudio/iDISP SDI values */
> -#define INTEL_DEV_NUM_IDA_MIN           4
> +/*
> + * sdw_dev_num_min: Set to non-zero to enable globally-unique peripheral IDs.
> + * The value is the minimum ID that will be allocated.
> + */
> +static int intel_dev_num_ida_min;
> +module_param_named(sdw_dev_num_min, intel_dev_num_ida_min, int, 0444);
> +MODULE_PARM_DESC(sdw_dev_num_min, "SoundWire Intel Master min globally-unique ID (0 to disable)");
>  
>  #define INTEL_MASTER_SUSPEND_DELAY_MS	3000
>  
> @@ -148,7 +153,7 @@ static int intel_link_probe(struct auxiliary_device *auxdev,
>  	cdns->msg_count = 0;
>  
>  	bus->link_id = auxdev->id;
> -	bus->dev_num_ida_min = INTEL_DEV_NUM_IDA_MIN;
> +	bus->dev_num_ida_min = intel_dev_num_ida_min;
>  	bus->clk_stop_timeout = 1;
>  
>  	sdw_cdns_probe(cdns);