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charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginatorOrg: aspeedtech.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: OSQPR06MB7252.apcprd06.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 9a3e511e-22d8-4825-ee4c-08de6550b9c5 X-MS-Exchange-CrossTenant-originalarrivaltime: 06 Feb 2026 07:24:12.1074 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 43d4aa98-e35b-4575-8939-080e90d5a249 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: y7t6CJDIs9tlXg8e5r2edu/TVcOIzKkusGT1p89o5VzZmDpWy1aNiBiCC+Y3qxWIjNsiW+V8LzFXmkFGA79EXnE8Fa2pcV0f0b5Hrcbx9NY= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PUZPR06MB5540 * Billy Tsai [260204 06:54]:=0A= > > Hi Tony,=0A= > >=0A= > > This series proposes a set of changes to pinctrl-single motivated by=0A= > > bit-per-mux SoC designs such as ASPEED AST2700 (per-pin DT encoding,=0A= > > aligned pinconf offsets, and allowing probe to continue when the MMIO= =0A= > > region is already reserved).=0A= > >=0A= > > Linus reviewed the series and noted that he would prefer a custom=0A= > > pinctrl driver using existing helpers and the pinmux =3D <...> DT=0A= > > property, rather than extending pinctrl-single, and suggested that the= =0A= > > pinctrl-single maintainers review the approach before any merge=0A= > > decision.=0A= > >=0A= > > I would appreciate your guidance on whether extending=0A= > > pinctrl-single in this direction is acceptable, or if the preference is= =0A= > > to pursue a dedicated driver instead.=0A= =0A= > I agree with what Linus that separate more targeted drivers are better=0A= > to avoid the drivers getting complex. With the GENERIC_PIN* helpers doing= =0A= > targeted drivers should be trivial.=0A= =0A= > My preference would be to move the bit-per-mux handling out of the=0A= > pinctrl-single driver into a separate pinctrl-single-bit type driver.=0A= > Seems that can still handle the cases where no hardware specific driver= =0A= > is needed.=0A= =0A= > This would simplify pinctrl-single driver quite a bit, and would make=0A= > the new driver quite simple too AFAIK.=0A= =0A= Hi Tony,=0A= =0A= Thanks for the clarification.=0A= =0A= I understand the preference is to keep pinctrl-single minimal and move=0A= the bit-per-mux handling into a separate, more targeted driver built on=0A= top of the GENERIC_PINMUX/GENERIC_PINCONF helpers, rather than extending=0A= pinctrl-single itself.=0A= =0A= Based on that, I=92ll look into refactoring this into a=0A= pinctrl-single-bit style driver that covers bit-per-mux / bit-per-pin=0A= layouts generically (including AST2700), while keeping pinctrl-single=0A= focused on the simpler register models.=0A= =0A= One additional point I=92d like to raise is the handling of pre-reserved=0A= MMIO regions.=0A= =0A= On AST2700 systems, the SCU register range containing the pinctrl=0A= registers is commonly reserved by a top-level syscon node or by firmware.= =0A= In this setup, devm_request_mem_region() can return -EBUSY even though the= =0A= registers are valid and intended to be shared, which currently causes the= =0A= driver to fail probing and leaves pinmux unconfigured.=0A= =0A= When moving to a separate targeted driver, would the preferred approach=0A= be to treat this condition as a warning and continue probing, or is there= =0A= an alternative pattern you=92d recommend for handling shared SCU-style=0A= register blocks in pinctrl drivers?=0A= =0A= Thanks,=0A= Billy=