netdev - Re: [PATCH v2] stmmac: CSR clock configuration fix

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Date:   Thu, 22 Dec 2016 17:06:59 +0000
From:   Joao Pinto <Joao.Pinto@...opsys.com>
To:     Phil Reid <preid@...ctromag.com.au>,
        Joao Pinto <Joao.Pinto@...opsys.com>, <peppe.cavallaro@...com>,
        <davem@...emloft.net>, <seraphin.bonnaffe@...com>
CC:     <hock.leong.kweh@...el.com>, <niklas.cassel@...s.com>,
        <pavel@....cz>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH v2] stmmac: CSR clock configuration fix

Às 4:57 PM de 12/22/2016, Phil Reid escreveu:
> On 22/12/2016 23:47, Joao Pinto wrote:
>>
>> Hello Phil,
>>
>> Às 3:42 PM de 12/22/2016, Phil Reid escreveu:
>>> G'day Joao,
>>>
>>> On 22/12/2016 20:38, Joao Pinto wrote:
>>>> When testing stmmac with my QoS reference design I checked a problem in the
>>>> CSR clock configuration that was impossibilitating the phy discovery, since
>>>> every read operation returned 0x0000ffff. This patch fixes the issue.
>>>>
>>>> Signed-off-by: Joao Pinto <jpinto@...opsys.com>
>>>> ---
>>>> changes v1->v2 (David Miller)
>>>> - DWMAC100 and DWMAC1000 csr clocks masks should also be fixed for the patch
>>>> to make sense
>>>>
>>>>  drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c | 2 +-
>>>>  drivers/net/ethernet/stmicro/stmmac/dwmac100_core.c  | 2 +-
>>>>  drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c    | 8 ++++----
>>>>  3 files changed, 6 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
>>>> b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
>>>> index b21d03f..94223c8 100644
>>>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
>>>> @@ -539,7 +539,7 @@ struct mac_device_info *dwmac1000_setup(void __iomem
>>>> *ioaddr, int mcbins,
>>>>      mac->mii.reg_shift = 6;
>>>>      mac->mii.reg_mask = 0x000007C0;
>>>>      mac->mii.clk_csr_shift = 2;
>>>> -    mac->mii.clk_csr_mask = 0xF;
>>>> +    mac->mii.clk_csr_mask = GENMASK(4, 2);
>>>
>>> Should this not be GENMASK(5,2)
>>
>> According to Universal MAC databook (valid for MAC100 and MAC1000), we have:
>>
>> Bits: 4:2
>> 000 60-100 MHz clk_csr_i/42
>> 001 100-150 MHz clk_csr_i/62
>> 010 20-35 MHz clk_csr_i/16
>> 011 35-60 MHz clk_csr_i/26
>> 100 150-250 MHz clk_csr_i/102
>> 101 250-300 MHz clk_csr_i/124
>> 110, 111 Reserved
>>
>> So only bits 2, 3 and 4 should be masked.
>>
>> Thanks.
>>
> But this is a change in behaviour from what was there isn't.
> Previous mask was 4 bits. now it's 3.
> 
> And for example the altera socfgpa implementation in the cyclone V has valid values
> for values 0x8-0xf, using bit 5:2.

According to the databook, bit 5 is reserved and RO. When reserved, it is
possible to customize. Is that the case? If there is hardware using the 5th bit
we can put it GENMASK(5, 2) with no problem.

> 
> 
> 
> 
>