Messages in this thread |  | | Subject | Re: [PATCH net-next v2] net: phy: dp83867: Add speed optimization feature | From | Dan Murphy <> | Date | Thu, 6 Feb 2020 16:13:09 -0600 |
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Heiner
On 2/5/20 3:16 PM, Heiner Kallweit wrote: > On 04.02.2020 19:13, Dan Murphy wrote: >> Set the speed optimization bit on the DP83867 PHY. >> This feature can also be strapped on the 64 pin PHY devices >> but the 48 pin devices do not have the strap pin available to enable >> this feature in the hardware. PHY team suggests to have this bit set. >> >> With this bit set the PHY will auto negotiate and report the link >> parameters in the PHYSTS register. This register provides a single >> location within the register set for quick access to commonly accessed >> information. >> >> In this case when auto negotiation is on the PHY core reads the bits >> that have been configured or if auto negotiation is off the PHY core >> reads the BMCR register and sets the phydev parameters accordingly. >> >> This Giga bit PHY can throttle the speed to 100Mbps or 10Mbps to accomodate a >> 4-wire cable. If this should occur the PHYSTS register contains the >> current negotiated speed and duplex mode. >> >> In overriding the genphy_read_status the dp83867_read_status will do a >> genphy_read_status to setup the LP and pause bits. And then the PHYSTS >> register is read and the phydev speed and duplex mode settings are >> updated. >> >> Signed-off-by: Dan Murphy <dmurphy@ti.com> >> --- >> v2 - Updated read status to call genphy_read_status first, added link_change >> callback to notify of speed change and use phy_set_bits - https://lore.kernel.org/patchwork/patch/1188348/ >> > As stated in the first review, it would be appreciated if you implement > also the downshift tunable. This could be a separate patch in this series. > Most of the implementation would be boilerplate code.
I looked at this today and there are no registers that allow tuning the downshift attempts. There is only a RO register that tells you how many attempts it took to achieve a link. So at the very least we could put in the get_tunable but there will be no set.
So we should probably skip this for this PHY.
Dan
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