linux-kernel - Re: [Intel-wired-lan] [PATCH iwl-next v1 1/8] igc: move IGC_TXDCTL_QUEUE_ENABLE and IGC_TXDCTL

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Message-ID: <dd046c43-1491-4d2c-b4f2-5946ac55441e@linux.intel.com>
Date: Tue, 29 Apr 2025 11:36:43 +0800
From: "Abdul Rahim, Faizal" <faizal.abdul.rahim@...ux.intel.com>
To: "Ruinskiy, Dima" <dima.ruinskiy@...el.com>,
 Tony Nguyen <anthony.l.nguyen@...el.com>,
 Przemek Kitszel <przemyslaw.kitszel@...el.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S . Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Vladimir Oltean <vladimir.oltean@....com>
Cc: intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Chwee-Lin Choong <chwee.lin.choong@...el.com>
Subject: Re: [Intel-wired-lan] [PATCH iwl-next v1 1/8] igc: move
 IGC_TXDCTL_QUEUE_ENABLE and IGC_TXDCTL_SWFLUSH

On 28/4/2025 3:01 pm, Ruinskiy, Dima wrote:
> On 28/04/2025 9:02, Faizal Rahim wrote:
>> Consolidate TXDCTL-related macros for better organization and readability.
>>
>> Signed-off-by: Faizal Rahim <faizal.abdul.rahim@...ux.intel.com>
>> ---
>>   drivers/net/ethernet/intel/igc/igc.h      | 6 ++++++
>>   drivers/net/ethernet/intel/igc/igc_base.h | 4 ----
>>   2 files changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/ 
>> intel/igc/igc.h
>> index 859a15e4ccba..e9d180eac015 100644
>> --- a/drivers/net/ethernet/intel/igc/igc.h
>> +++ b/drivers/net/ethernet/intel/igc/igc.h
>> @@ -492,6 +492,12 @@ static inline u32 igc_rss_type(const union 
>> igc_adv_rx_desc *rx_desc)
>>   #define IGC_RX_WTHRESH            4
>>   #define IGC_TX_WTHRESH            16
>> +/* Additional Transmit Descriptor Control definitions */
>> +/* Ena specific Tx Queue */
>> +#define IGC_TXDCTL_QUEUE_ENABLE    0x02000000
>> +/* Transmit Software Flush */
>> +#define IGC_TXDCTL_SWFLUSH    0x04000000
>> +
>>   #define IGC_RX_DMA_ATTR \
>>       (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING)
>> diff --git a/drivers/net/ethernet/intel/igc/igc_base.h b/drivers/net/ 
>> ethernet/intel/igc/igc_base.h
>> index 6320eabb72fe..4a56c634977b 100644
>> --- a/drivers/net/ethernet/intel/igc/igc_base.h
>> +++ b/drivers/net/ethernet/intel/igc/igc_base.h
>> @@ -86,10 +86,6 @@ union igc_adv_rx_desc {
>>       } wb;  /* writeback */
>>   };
>> -/* Additional Transmit Descriptor Control definitions */
>> -#define IGC_TXDCTL_QUEUE_ENABLE    0x02000000 /* Ena specific Tx Queue */
>> -#define IGC_TXDCTL_SWFLUSH    0x04000000 /* Transmit Software Flush */
>> -
>>   /* Additional Receive Descriptor Control definitions */
>>   #define IGC_RXDCTL_QUEUE_ENABLE    0x02000000 /* Ena specific Rx Queue */
>>   #define IGC_RXDCTL_SWFLUSH        0x04000000 /* Receive Software Flush */
> 
> Is there an intrinsic value for moving these definitions from one H file to 
> another? And if so, why move the Tx defs and leave the Rx defs where they are?

Hi Dima,

I moved and refactored the TXDCTL macros because this patch series
modifies the TXDCTL register, specifically setting new bitfields.
Consolidating `IGC_TXDCTL_QUEUE_ENABLE` and `IGC_TXDCTL_SWFLUSH`
alongside the existing TXDCTL macros improves readability and makes it
easier to cross-reference the TXDCTL bitfield mapping, as documented in
Section 8.11.16 of the i226 Software User Manual. The grouping now
matches that layout directly:

#define IGC_TXDCTL_PTHRESH_MASK       GENMASK(4, 0)
#define IGC_TXDCTL_HTHRESH_MASK        GENMASK(12, 8)
#define IGC_TXDCTL_WTHRESH_MASK        GENMASK(20, 16)
#define IGC_TXDCTL_QUEUE_ENABLE_MASK   GENMASK(25, 25)
#define IGC_TXDCTL_SWFLUSH_MASK        GENMASK(26, 26)
#define IGC_TXDCTL_PRIORITY_MASK       GENMASK(27, 27)

Since RXDCTL is a separate register with its own bitfield mapping
section in the i226 Software User Manual, and this patch series does
not modify it, I left the RXDCTL macros untouched. They are used
independently in separate functions within the driver.

That said, I can move the RXDCTL macros as well for consistency.