linux-kernel - Re: [PATCH 1/2] slimbus: stream: add stream support

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Message-ID: <20180622125050.GO27187@vkoul-mobl>
Date:   Fri, 22 Jun 2018 18:20:50 +0530
From:   Vinod <vkoul@...nel.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     gregkh@...uxfoundation.org, broonie@...nel.org,
        sdharia@...cinc.com, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, alsa-devel@...a-project.org,
        ctatlor97@...il.com
Subject: Re: [PATCH 1/2] slimbus: stream: add stream support

On 21-06-18, 14:40, Srinivas Kandagatla wrote:
> This patch adds support to SLIMbus stream apis for slimbus device.
> SLIMbus streaming involves adding support to Data Channel Management and
> channel Reconfiguration Messages to slim core plus few stream apis.
> >From slim device side the apis are very simple mostly inline with other
  ^^
Bad char >

> +/**
> + * enum slim_port_direction: SLIMbus port direction

blank line here makes it more readable

> +/**
> + * struct slim_presence_rate - Presense Rate table for all Natural Frequencies
> + *	The Presense rate of a constant bitrate stram is mean flow rate of the
                                                ^^^^^
Do you mean stream?

> +static struct slim_presence_rate {
> +	int rate;
> +	int pr_code;
> +} prate_table[] = {
> +	{12000,		0x01},
> +	{24000,		0x02},
> +	{48000,		0x03},
> +	{96000,		0x04},
> +	{192000,	0x05},
> +	{384000,	0x06},
> +	{768000,	0x07},
> +	{110250,	0x09},
> +	{220500,	0x0a},
> +	{441000,	0x0b},
> +	{882000,	0x0c},
> +	{176400,	0x0d},
> +	{352800,	0x0e},
> +	{705600,	0x0f},
> +	{4000,		0x10},
> +	{8000,		0x11},
> +	{16000,		0x12},
> +	{32000,		0x13},
> +	{64000,		0x14},
> +	{128000,	0x15},
> +	{256000,	0x16},
> +	{512000,	0x17},

this table values are indices, so how about using only rate and removing
pr_code and use array index for that, saves half the space..

> +struct slim_stream_runtime *slim_stream_allocate(struct slim_device *dev,
> +						 const char *name)
> +{
> +	struct slim_stream_runtime *rt;
> +	unsigned long flags;
> +
> +	rt = kzalloc(sizeof(*rt), GFP_KERNEL);
> +	if (!rt)
> +		return ERR_PTR(-ENOMEM);
> +
> +	rt->name = kasprintf(GFP_KERNEL, "slim-%s", name);
> +	if (!rt->name) {
> +		kfree(rt);
> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	rt->dev = dev;
> +	rt->state = SLIM_STREAM_STATE_ALLOCATED;
> +	spin_lock_irqsave(&dev->stream_list_lock, flags);
> +	list_add_tail(&rt->node, &dev->stream_list);
> +	spin_unlock_irqrestore(&dev->stream_list_lock, flags);

Any reason for _irqsave variant? Do you expect stream APIs to be called
from ISR?

> +/*
> + * slim_stream_prepare() - Prepare a SLIMbus Stream
> + *
> + * @rt: instance of slim stream runtime to configure
> + * @cfg: new configuration for the stream
> + *
> + * This API will configure SLIMbus stream with config parameters from cfg.
> + * return zero on success and error code on failure. From ASoC DPCM framework,
> + * this state is linked to hw_params()/prepare() operation.

so would this be called from either.. btw prepare can be invoked
multiple times, so that should be taken into consideration by caller.

> + */
> +int slim_stream_prepare(struct slim_stream_runtime *rt,
> +			struct slim_stream_config *cfg)
> +{
> +	struct slim_controller *ctrl = rt->dev->ctrl;
> +	struct slim_port *port;
> +	int num_ports, i, port_id;
> +
> +	num_ports = hweight32(cfg->port_mask);
> +	rt->ports = kcalloc(num_ports, sizeof(*port), GFP_ATOMIC);

since this is supposed to be invoked in hw_params()/prepare, why would
we need GFP_ATOMIC here?

> +static int slim_activate_channel(struct slim_stream_runtime *stream,
> +				 struct slim_port *port)
> +{
> +	struct slim_device *sdev = stream->dev;
> +	struct slim_val_inf msg = {0, 0, NULL, NULL};
> +	u8 mc = SLIM_MSG_MC_NEXT_ACTIVATE_CHANNEL;
> +	DEFINE_SLIM_LDEST_TXN(txn, mc, 5, stream->dev->laddr, &msg);
> +	u8 wbuf[1];
> +
> +	txn.msg->num_bytes = 1;
> +	txn.msg->wbuf = wbuf;
> +	wbuf[0] = port->ch.id;
> +	port->ch.state = SLIM_CH_STATE_ACTIVE;
> +
> +	return slim_do_transfer(sdev->ctrl, &txn);
> +}

how about adding a macro for sending message, which fills slim_val_inf
and you invoke that with required parameters to be filled.

> +/*
> + * slim_stream_enable() - Enable a prepared SLIMbus Stream

Do you want to check if it is already prepared ..?

> +/**
> + * slim_stream_direction: SLIMbus stream direction
> + *
> + * @SLIM_STREAM_DIR_PLAYBACK: Playback
> + * @SLIM_STREAM_DIR_CAPTURE: Capture
> + */
> +enum slim_stream_direction {
> +	SLIM_STREAM_DIR_PLAYBACK = 0,
> +	SLIM_STREAM_DIR_CAPTURE,

this is same as SNDRV_PCM_STREAM_PLAYBACK, so should we use that here?
-- 
~Vinod