linux-kernel - Re: [PATCH v4 4/5] net: wan: fsl_qmc_hdlc: Add runtime timeslots changes support

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Date: Fri, 23 Feb 2024 17:46:35 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Yury Norov
 <yury.norov@...il.com>, Rasmus Villemoes <linux@...musvillemoes.dk>,
 linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, Andrew Lunn <andrew@...n.ch>, Mark Brown
 <broonie@...nel.org>, Christophe Leroy <christophe.leroy@...roup.eu>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v4 4/5] net: wan: fsl_qmc_hdlc: Add runtime timeslots
 changes support

Hi Andy,

On Thu, 22 Feb 2024 17:47:34 +0200
Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

..

> > +static int qmc_hdlc_xlate_slot_map(struct qmc_hdlc *qmc_hdlc,
> > +				   u32 slot_map, struct qmc_chan_ts_info *ts_info)
> > +{
> > +	DECLARE_BITMAP(ts_mask_avail, 64);
> > +	DECLARE_BITMAP(ts_mask, 64);
> > +	DECLARE_BITMAP(map, 64);  
> 
> Perhaps more 1:1 naming?
> 
> 	DECLARE_BITMAP(rx_ts_mask_avail, 64);
> 	DECLARE_BITMAP(tx_ts_mask, 64);
> 	DECLARE_BITMAP(slot_map, 64);

I disagree.

I first check that ts_info->rx_ts_mask_avail and ts_info->tx_ts_mask_avail are
identical then I use one of them to create the ts_mask_avail.
Then I compute the ts_mask and update both ts_info->tx_ts_mask and
ts_info->rx_ts_mask.

ts_mask_avail and ts_mask bitmaps are used for tx and rx.
I could name them txrx_ts_mask* but that doesn't do much.

For DECLARE_BITMAP(slot_map, 64), slot_map is the name of the function
parameter...
I think we can keep 'map' for the bitmap here.

> 
> > +	/* Tx and Rx available masks must be identical */
> > +	if (ts_info->rx_ts_mask_avail != ts_info->tx_ts_mask_avail) {
> > +		dev_err(qmc_hdlc->dev, "tx and rx available timeslots mismatch (0x%llx, 0x%llx)\n",
> > +			ts_info->rx_ts_mask_avail, ts_info->tx_ts_mask_avail);
> > +		return -EINVAL;
> > +	}
> > +
> > +	bitmap_from_u64(ts_mask_avail, ts_info->rx_ts_mask_avail);
> > +	bitmap_from_u64(map, slot_map);
> > +	bitmap_scatter(ts_mask, map, ts_mask_avail, 64);
> > +
> > +	if (bitmap_weight(ts_mask, 64) != bitmap_weight(map, 64)) {
> > +		dev_err(qmc_hdlc->dev, "Cannot translate timeslots %*pb -> (%*pb, %*pb)\n",
> > +			64, map, 64, ts_mask_avail, 64, ts_mask);  
> 
> 
> You can save a bit of code and stack:

Will be updated in the next iteration.

..

> > +	ret = qmc_chan_get_ts_info(qmc_hdlc->qmc_chan, &ts_info);
> > +	if (ret) {
> > +		dev_err(qmc_hdlc->dev, "get QMC channel ts info failed %d\n", ret);
> > +		return ret;  
> 
> 		return dev_err_probe(...);

Will be updated too :)

> 
> > +	}  
> 

Thanks for the review,
Hervé