netdev - RE: [PATCH iwl-next 1/5] ice: use rd32_poll_timeout_atomic in ice_read_phy_tstamp_ll

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Message-ID: <CO1PR11MB50898F72BE794A0187649EA3D6312@CO1PR11MB5089.namprd11.prod.outlook.com>
Date: Fri, 6 Dec 2024 20:15:00 +0000
From: "Keller, Jacob E" <jacob.e.keller@...el.com>
To: Simon Horman <horms@...nel.org>, "Nadezhdin, Anton"
	<anton.nadezhdin@...el.com>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, "richardcochran@...il.com"
	<richardcochran@...il.com>, "Kolacinski, Karol" <karol.kolacinski@...el.com>,
	"Olech, Milena" <milena.olech@...el.com>
Subject: RE: [PATCH iwl-next 1/5] ice: use rd32_poll_timeout_atomic in
 ice_read_phy_tstamp_ll_e810



> -----Original Message-----
> From: Simon Horman <horms@...nel.org>
> Sent: Friday, December 6, 2024 5:30 AM
> To: Nadezhdin, Anton <anton.nadezhdin@...el.com>
> Cc: intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org; Nguyen, Anthony L
> <anthony.l.nguyen@...el.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>; richardcochran@...il.com; Keller, Jacob E
> <jacob.e.keller@...el.com>; Kolacinski, Karol <karol.kolacinski@...el.com>; Olech,
> Milena <milena.olech@...el.com>
> Subject: Re: [PATCH iwl-next 1/5] ice: use rd32_poll_timeout_atomic in
> ice_read_phy_tstamp_ll_e810
> 
> On Wed, Dec 04, 2024 at 01:03:44PM -0500, Anton Nadezhdin wrote:
> > From: Jacob Keller <jacob.e.keller@...el.com>
> >
> > The ice_read_phy_tstamp_ll_e810 function repeatedly reads the PF_SB_ATQBAL
> > register until the TS_LL_READ_TS bit is cleared. This is a perfect
> > candidate for using rd32_poll_timeout. However, the default implementation
> > uses a sleep-based wait.
> >
> > Add a new rd32_poll_timeout_atomic macro which is based on the non-
> sleeping
> > read_poll_timeout_atomic implementation. Use this to replace the loop
> > reading in the ice_read_phy_tstamp_ll_e810 function.
> >
> > This will also be used in the future when low latency PHY timer updates are
> > supported.
> >
> > Co-developed-by: Karol Kolacinski <karol.kolacinski@...el.com>
> > Signed-off-by: Karol Kolacinski <karol.kolacinski@...el.com>
> > Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> > Reviewed-by: Milena Olech <milena.olech@...el.com>
> > Signed-off-by: Anton Nadezhdin <anton.nadezhdin@...el.com>
> > ---
> >  drivers/net/ethernet/intel/ice/ice_osdep.h  |  3 +++
> >  drivers/net/ethernet/intel/ice/ice_ptp_hw.c | 30 +++++++++------------
> >  drivers/net/ethernet/intel/ice/ice_ptp_hw.h |  2 +-
> >  3 files changed, 17 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/ice/ice_osdep.h
> b/drivers/net/ethernet/intel/ice/ice_osdep.h
> > index b9f383494b3f..9bb343de80a9 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_osdep.h
> > +++ b/drivers/net/ethernet/intel/ice/ice_osdep.h
> > @@ -26,6 +26,9 @@
> >
> >  #define rd32_poll_timeout(a, addr, val, cond, delay_us, timeout_us) \
> >  	read_poll_timeout(rd32, val, cond, delay_us, timeout_us, false, a, addr)
> > +#define rd32_poll_timeout_atomic(a, addr, val, cond, delay_us, timeout_us) \
> > +	read_poll_timeout_atomic(rd32, val, cond, delay_us, timeout_us, false, \
> > +				 a, addr)
> >
> >  #define ice_flush(a)		rd32((a), GLGEN_STAT)
> >  #define ICE_M(m, s)		((m ## U) << (s))
> > diff --git a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
> b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
> > index e55aeab0975c..b9cf8ce9644a 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
> > +++ b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
> > @@ -4868,32 +4868,28 @@ static int
> >  ice_read_phy_tstamp_ll_e810(struct ice_hw *hw, u8 idx, u8 *hi, u32 *lo)
> >  {
> >  	u32 val;
> > -	u8 i;
> > +	u8 err;
> >
> >  	/* Write TS index to read to the PF register so the FW can read it */
> >  	val = FIELD_PREP(TS_LL_READ_TS_IDX, idx) | TS_LL_READ_TS;
> >  	wr32(hw, PF_SB_ATQBAL, val);
> >
> >  	/* Read the register repeatedly until the FW provides us the TS */
> > -	for (i = TS_LL_READ_RETRIES; i > 0; i--) {
> > -		val = rd32(hw, PF_SB_ATQBAL);
> > -
> > -		/* When the bit is cleared, the TS is ready in the register */
> > -		if (!(FIELD_GET(TS_LL_READ_TS, val))) {
> > -			/* High 8 bit value of the TS is on the bits 16:23 */
> > -			*hi = FIELD_GET(TS_LL_READ_TS_HIGH, val);
> > +	err = rd32_poll_timeout_atomic(hw, PF_SB_ATQBAL, val,
> > +				       !FIELD_GET(TS_LL_READ_TS, val),
> > +				       10, TS_LL_READ_TIMEOUT);
> 
> Hi Jakob and Karol,
> 
> A minor nit from my side: rd32_poll_timeout_atomic may return a negative
> error value but err is unsigned. This doesn't seem ideal.
> 
> Flagged by Smatch
> 

Yep, err should just be an integer here.

Thanks,
Jake

> > +	if (err) {
> > +		ice_debug(hw, ICE_DBG_PTP, "Failed to read PTP timestamp using
> low latency read\n");
> > +		return err;
> > +	}
> >
> > -			/* Read the low 32 bit value and set the TS valid bit */
> > -			*lo = rd32(hw, PF_SB_ATQBAH) | TS_VALID;
> > -			return 0;
> > -		}
> > +	/* High 8 bit value of the TS is on the bits 16:23 */
> > +	*hi = FIELD_GET(TS_LL_READ_TS_HIGH, val);
> >
> > -		udelay(10);
> > -	}
> > +	/* Read the low 32 bit value and set the TS valid bit */
> > +	*lo = rd32(hw, PF_SB_ATQBAH) | TS_VALID;
> >
> > -	/* FW failed to provide the TS in time */
> > -	ice_debug(hw, ICE_DBG_PTP, "Failed to read PTP timestamp using low
> latency read\n");
> > -	return -EINVAL;
> > +	return 0;
> >  }
> >
> >  /**
> 
> ...