netdev - Re: [PATCH v3 net-next 13/19] ionic: Add initial ethtool support

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Message-ID: <20190718172823.GH25635@lunn.ch>
Date:   Thu, 18 Jul 2019 19:28:23 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Shannon Nelson <snelson@...sando.io>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH v3 net-next 13/19] ionic: Add initial ethtool support

On Thu, Jul 18, 2019 at 10:05:23AM -0700, Shannon Nelson wrote:
> On 7/17/19 8:21 PM, Andrew Lunn wrote:
> >On Tue, Jul 09, 2019 at 03:42:39PM -0700, Shannon Nelson wrote:
> >>On 7/8/19 7:27 PM, Andrew Lunn wrote:
> >>>>+static int ionic_get_module_eeprom(struct net_device *netdev,
> >>>>+				   struct ethtool_eeprom *ee,
> >>>>+				   u8 *data)
> >>>>+{
> >>>>+	struct lif *lif = netdev_priv(netdev);
> >>>>+	struct ionic_dev *idev = &lif->ionic->idev;
> >>>>+	struct xcvr_status *xcvr;
> >>>>+	u32 len;
> >>>>+
> >>>>+	/* copy the module bytes into data */
> >>>>+	xcvr = &idev->port_info->status.xcvr;
> >>>>+	len = min_t(u32, sizeof(xcvr->sprom), ee->len);
> >>>>+	memcpy(data, xcvr->sprom, len);
> >>>Hi Shannon
> >>>
> >>>This also looks odd. Where is the call into the firmware to get the
> >>>eeprom contents? Even though it is called 'eeprom', the data is not
> >>>static. It contains real time diagnostic values, temperature, transmit
> >>>power, receiver power, voltages etc.
> >>idev->port_info is a memory mapped space that the device keeps up-to-date.
> >Hi Shannon
> >
> >It at least needs a comment. How frequently does the device update
> >this chunk of memory? It would be good to comment about that as
> >well. Or do MMIO reads block while i2c operations occur to update the
> >memory?
> 
> The device keeps this updated when changes happen internally so that there
> is no need to block on MMIO read. 

Hi Shannon

I'm thinking about the diagnostic page. RX and TX power, temperature,
alarms etc. These are real time values, so you should read them on
demand, or at last only cache them for a short time.

	Andrew