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X-OriginatorOrg: ti.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jan 2026 04:34:30.8179 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: be4a9e5d-9b6c-4312-295f-08de596f8914 X-MS-Exchange-CrossTenant-Id: e5b49634-450b-4709-8abb-1e2b19b982b7 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=e5b49634-450b-4709-8abb-1e2b19b982b7;Ip=[198.47.23.194];Helo=[lewvzet200.ext.ti.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF00017090.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH5PR10MB997710 On Wed, 2026-01-21 at 14:22 +0100, Andrew Lunn wrote: > On Wed, Jan 21, 2026 at 11:15:50AM +0530, Siddharth Vadapalli wrote: > > MAC Ports 1 and 2 of the CPSW3G Ethernet Switch in the AM62D2 SoC are b= oth > > connected to different instances of the DP83867 Ethernet PHY on the AM6= 2D2 > > EVM, with the 'phy-mode' set to 'rgmii-id'. The DP83867 Ethernet PHY ha= s to > > add a 2 nanosecond delay on receive (from wire) based on the EVM design= . > >=20 > > Since the device driver for the DP83867 Ethernet PHY coincidentally ass= umes > > that a 2 nanosecond receive delay has to be added in the absence of the > > 'ti,rx-internal-delay' property, Ethernet is functional. > >=20 > > However, since the device-tree is intended to describe the Hardware, an= d, > > the device driver for the DP83867 Ethernet PHY may change in the future= , > > add the 'ti,rx-internal-delay' property and assign it the value > > 'DP83867_RGMIIDCTL_2_00_NS' which corresponds to a 2 nanosecond > > delay. >=20 > The driver will not change. Doing so will break boards, causing Ok. > regressions. Also, passing PHY_INTERFACE_MODE_RGMII_ID to the PHY > means the PHY should add 2ns, or the closet it can achieve. The PHY > driver does not coincidentally assumes that a 2 nanosecond receive > delay is required, it is required a 2ns delay is added. A default of 2ns is chosen and is overridden by the value specified in the device-tree via the 'ti,rx-internal-delay' property. So it is ultimately what is described in the device-tree that dictates the Hardware and the configuration that the driver should perform. I agree that in this case the 2ns delay doesn't have to be described in the device-tree for functionality. But my question is whether it is wrong or unexpected to specify the delay in the device-tree when it is simply describing the Hardware? For further context, U-Boot (Bootloader) uses the Linux device-tree. The U- Boot PHY driver relies on the device-tree to specify the delay. Is it incorrect to rely on the device-tree description for configuring the Hardware? Unlike Linux PHY driver, the U-Boot PHY driver doesn't assign a default of 2ns. Instead, it asks for the delay to be specified in the device-tree. While this may seem like a 'bug' in the U-Boot PHY driver, given that a proper and complete description of the Hardware is all that the driver expects, wouldn't the proper 'fix' be to simply describe the same in the device-tree? Please let me know what you think. >=20 > So this patch is pointless. >=20 > Please drop it. This is required for U-Boot as pointed out above. The reason I didn't mention it in the commit message earlier is because the patch is simply describing the Hardware which is what the device-tree does. Mentioning U- Boot would have taken the conversation in a different direction where the reader starts questioning why U-Boot PHY driver can't have a default the way Linux PHY driver does. That would be a valid point if the patch was violating the device-tree convention or doing something unexpected. Since that isn't the case, I have kept the description simple, positioning this patch as a 'fix' in terms of explicitly describing the Hardware through the device-tree, rather than depending on the driver defaults. Regards, Siddharth.