Re: [PATCH/RFC 01/02] ravb: Do not announce 100Mbps HDX as supported

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On 07/19/2018 08:25 PM, Magnus Damm wrote:

>>> From: Magnus Damm <damm+renesas@xxxxxxxxxxxxx>
>>>
>>> According to the data sheet the Ethernet-AVB hardware in R-Car Gen3
>>> and R-Car Gen2 SoCs do not support half duplex operation. So update
>>> the driver to mark 100Mbit HDX as unsupported.
>>
>>    What about 1000Mbit HDX?
> 
> For Twister Pair I believe 10 and 100 Mbps come in HDX and FDX flavors
> while 1 Gbps is HDX-only.

   Are we limited to TP?

> https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair
> 
>>> Not-Yet-Signed-off-by: Magnus Damm <damm+renesas@xxxxxxxxxxxxx>
>>> ---
>>>
>>>  Written on top of renesas-drivers-2018-07-17-v4.18-rc5
>>>
>>>  drivers/net/ethernet/renesas/ravb_main.c |    4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> --- 0001/drivers/net/ethernet/renesas/ravb_main.c
>>> +++ work/drivers/net/ethernet/renesas/ravb_main.c     2018-07-19 19:18:38.210607110 +0900
>>> @@ -1066,8 +1066,8 @@ static int ravb_phy_init(struct net_devi
>>>               netdev_info(ndev, "limited PHY to 100Mbit/s\n");
>>>       }
>>>
>>> -     /* 10BASE is not supported */
>>> -     phydev->supported &= ~PHY_10BT_FEATURES;
>>> +     /* Nether 10BASE nor half duplex is supported */
>>
>>    Neither. s/is/are/?
>>
>>> +     phydev->supported &= ~(PHY_10BT_FEATURES | SUPPORTED_100baseT_Half);
>>
>>    I think you missed SUPPORTED_1000baseT_Half.
> 
> Perhaps so, but in reality all our boards use a PHY with Twisted Pair

   I don't think we should limit ourselves to the development boards...

> cables so SUPPORTED_1000baseT_Half doesn't exist in reality. That
> aside, I suspect the PHY layer is designed to support more than just
> Ethernet-over-TP so that's the reason for that particular constant and
> all the other stuff in phy.h.

   Yes, probably. I'd like the code to be formally correct, so you need
also to mask off 1000Gbit HDX.

>> [garbage skipped]
> 
> You mean the rest of the driver? =)

   Naw. Some other mail got attached at the end of this patch -- probably,
it's just me... :-)
 
> Cheers,
> 
> / magnus

MBR, Sergei



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