Message-ID: <372cbc16-c2da-b9b9-9ac2-f7a2572c426d@seco.com>
Date:   Thu, 23 Feb 2023 12:13:06 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.4.0
Subject: Re: [PATCH net-next] net: pcs: tse: port to pcs-lynx
Content-Language: en-US
To:     Andrew Lunn <andrew@lunn.ch>,
        Vladimir Oltean <vladimir.oltean@nxp.com>
Cc:     Maxime Chevallier <maxime.chevallier@bootlin.com>,
        davem@davemloft.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
        Jakub Kicinski <kuba@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org,
        Ioana Ciornei <ioana.ciornei@nxp.com>
References: <20230210190949.1115836-1-maxime.chevallier@bootlin.com>
 <20230210190949.1115836-1-maxime.chevallier@bootlin.com>
 <20230210193159.qmbtvwtx6kqagvxy@skbuf> <Y+ai3zHMUCDcxqxP@lunn.ch>
From:   Sean Anderson <sean.anderson@seco.com>
In-Reply-To: <Y+ai3zHMUCDcxqxP@lunn.ch>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?SVpFeFR2MzdqaDFzTGtHWGV1QUpvbXdHekJxZm1Oc2hFM2VpRzZPWTBCM3RS?=
 =?utf-8?B?eVNacXhQVzgwVm1pdXIzaCtzdXo2VXJVM2NuZzIreFlOL1RkOGJTaFpuNWRj?=
 =?utf-8?B?M0JrOFpKSDNiTy9Vci9oUUlleTdsWEtVQ0ZYYlFHS1o4OERJOHlQVHZmanh1?=
 =?utf-8?B?ejUvZWtXckQvVjlaQ1RpK0tFSk5YSUVabWMvYzNmdUxQbkF5bEE0QkNEaHds?=
 =?utf-8?B?d1RIUFZlUDcwaWdIemljYjJaUHlQOTlkZ3I1MkF4cU4vdTBZSExpcmJwZElI?=
 =?utf-8?B?QkFCZUc2UVBGQThUU0xDMjBLWmNMU1lqMHRaWHVFZWpOUmRSKytySU1BRmZx?=
 =?utf-8?B?bHV6TGNHaHBhRFV1MzlsZjYvNDZpVG5ITklGWXlWZ0dJOE1oYlFQVkpmVjU0?=
 =?utf-8?B?OFpVeFNyaUVTN1c3NjlPNVU2blRmejZvdzZrR21vY2UzQVVtaHExYUwzMlpT?=
 =?utf-8?B?L2o5NERvME9ZS3pGRkZaTi9hZmxZS2gxdXp1U3FtUGZLaEIvZ1VnL2pQSmFQ?=
 =?utf-8?B?WjZFNTJFRmp6TDlWamdIL0lURmg2Rk9zVzkwb2Jiemw2dlVuY21NaHZsZ0lL?=
 =?utf-8?B?MHZPWUJaTEwvZlFpb1E5MktBdklQc2FVNW9FWk4remJYeU5ERCtwcDl6MHd2?=
 =?utf-8?B?by82OUZZL3hoN2E4SUprMWJ0WUZvMkR5NWhzY1lkSTFoN09SWkJ6R2lzOWlu?=
 =?utf-8?B?RXRCVEEyT2dlblZ1UUc1akNRd2FkMld3UmZJS2NuYWJWbTZWZUdlSFJySGxD?=
 =?utf-8?B?dlRTcnRHVS9YSS9tUGNJRHAzdG15bXI3MmJsSS9KTndMc0NVeTVmemxwc2ZI?=
 =?utf-8?B?QWNwajBwVHJ4RndhZmh0WDJnc2l5bzFGbGtOYTJOa1hWQytIa2lSNk1PTVVD?=
 =?utf-8?B?bDVCQ1gyRGN1SmZPeDRmOFV5RWRDOS9TWGV6SVpMTUg1NmJxUDNEbmp0NzV3?=
 =?utf-8?B?eG9Tb1QyeXhiQTVyNHV0MWsyTjljNWd4VTJKS2N0WUk2QVpXL2dkTkIvdFlZ?=
 =?utf-8?B?V01EcEduY1g1U1RuWUdtQTdidGZGRDNGVnYwOHdlekRWQWtJbVk5OTFZdWtK?=
 =?utf-8?B?UDRrVkZjTUhlbUZhcUQ5WkpaWEwvdi80aHg4eXEyL05ERXVUU3A2VG9Kdm1i?=
 =?utf-8?B?UkJTNkNiM1JIdjdlRDhjVjlHY2xTSklUUXFjdjRMaXFPZ3NMWGtDZFpkSlMy?=
 =?utf-8?B?dWUxc3hDdnBuelV4eXJqTXpJTWFCc2Q5N0dwdHd5UHIxN1laMWFyRFZKRUpQ?=
 =?utf-8?B?MHM0eGM1THRxbUhObjZIOUN6enE0S084bU5lS1Y4dzc1TzErKzhvMmJCYVVu?=
 =?utf-8?B?a05sNWpFSXVCRzVaVERqQzVQUkNubGVyN3hvak9ac1ZVQ1UzUzZpT3R5NXhn?=
 =?utf-8?B?UklBWGc5NTgxOGJOZGd3K05oRlBlNTFLUnFJb0g5WnNCZ1ZJb3UvcDJGMFdX?=
 =?utf-8?B?SVVVYzh3dzZhNEtiR3I5d2V3cnZHL3NkOWh0ekQ5QmNLQlUxdGk0bUhRbytm?=
 =?utf-8?B?VHYxVGE0bk5nU2tVQUV2U25UdEs0YmVKbWM1ZUJwTytSeE1MOWoxdUVuWUlD?=
 =?utf-8?B?VWExblFrZEhkbEx6R2dmTHNncXFmS1RhKzRBUHJ0S2ZMTnJ3VmdMTWJad1Fh?=
 =?utf-8?B?akJiUjl1Wnljems1b29Dc2sza3l1TVc0ckdZTzJwTWEyMEpJeUNweEIvdEJF?=
 =?utf-8?B?dFljYXI5cXhxZzYvQ3lNTzR4cGpmRXpIZ0FLSzlGOXJqTFJ1SjZXNDdmYlVt?=
 =?utf-8?B?NVcxSDBKOWV0WTJBL2tVS3ViZUprSDAzZW1pRkxRU0pkTXJobVRMVFhRUmpN?=
 =?utf-8?B?WHloWS9zWXlEcElpZkQ4bTVtVFg1UCt5alBYWk1kY1FJQW42bEVBdGJxbGdZ?=
 =?utf-8?B?M1BKVUlrbFAxODB6SVA3UzdSa0hsL1ljMGsrRWQ1ekFRZ2FvbXlreTk1ck9w?=
 =?utf-8?B?c1NIRTZPbzJTMGdnOWpreVM1U0J3U3hORnZCOVI3VDAyRUpMQ2MyYm1YRUFn?=
 =?utf-8?B?WTlFWVpTc2lqbTg5Y3psSm5OVk51R0E2OGwzc2tQWndnYThkUkVCT0hiRU4x?=
 =?utf-8?B?alk3Z205ZHlveW5jS0NpWTROUlZDeE1tTnlINVBtRnpBc1F5OGJGNkdQNWdR?=
 =?utf-8?B?ZUhQSitRUytPLzhZMzV2NFRpNW5CMjZzdXZmZXlwMzJjeXQrRkdVZGU1OHNj?=
 =?utf-8?B?V1E9PQ==?=
X-OriginatorOrg: seco.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 250cc36c-a3b4-4a8a-d093-08db15c13e77
X-MS-Exchange-CrossTenant-AuthSource: DB9PR03MB8847.eurprd03.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Feb 2023 17:13:12.5686
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: bebe97c3-6438-442e-ade3-ff17aa50e733
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: y6NxsZz05EFXgdsuvnqUTEzq+DVJ4XaIPO5TzwtATNt62h+W8AJHibjSfO5YqMC2TfuvnSKi0qvcjfk0McVEfA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS8PR03MB7110
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2/10/23 15:02, Andrew Lunn wrote:
> On Fri, Feb 10, 2023 at 09:31:59PM +0200, Vladimir Oltean wrote:
>> On Fri, Feb 10, 2023 at 08:09:49PM +0100, Maxime Chevallier wrote:
>> > When submitting the initial driver for the Altera TSE PCS, Russell King
>> > noted that the register layout for the TSE PCS is very similar to the
>> > Lynx PCS. The main difference being that TSE PCS's register space is
>> > memory-mapped, whereas Lynx's is exposed over MDIO.
>> > 
>> > Convert the TSE PCS to reuse the whole logic from Lynx, by allowing
>> > the creation of a dummy MDIO bus, and a dummy MDIO device located at
>> > address 0 on that bus. The MAC driver that uses this PCS must provide
>> > callbacks to read/write the MMIO.
>> > 
>> > Also convert the Altera TSE MAC driver to this new way of using the TSE
>> > PCS.
>> > 
>> > Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
>> > ---
>> >  drivers/net/ethernet/altera/altera_tse.h      |   2 +-
>> >  drivers/net/ethernet/altera/altera_tse_main.c |  50 ++++-
>> >  drivers/net/pcs/Kconfig                       |   4 +
>> >  drivers/net/pcs/pcs-altera-tse.c              | 194 +++++++-----------
>> >  include/linux/pcs-altera-tse.h                |  22 +-
>> >  5 files changed, 142 insertions(+), 130 deletions(-)
>> 
>> The glue layer is larger than the duplicated PCS code? :(
> 
> I was wondering if the glue could actually be made generic. The kernel
> has a number of reasonably generic MMIO device drivers, which are just
> given an address range and assume a logical mapping.
> 
> Could this be made into a generic MDIO MMIO bus driver, which just
> gets configured with a base address, and maybe a stride between
> registers?

That's what I originally considered for MACB [1], but I ended up creating
the various encode/decode functions because the PCS didn't have an MDIO
counterpart [2].

--Sean

[1] https://lore.kernel.org/netdev/20211004191527.1610759-11-sean.anderson@seco.com/
    This patch doesn't have a mmap-mdio, as I dropped it before submission.
[2] https://lore.kernel.org/netdev/20211004191527.1610759-8-sean.anderson@seco.com/