From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [RFC PATCH 0/2] serial: 8250_dw: IO space + polling mode support Date: Mon, 26 Feb 2018 13:28:37 +0200 Message-ID: <1519644517.10722.179.camel@linux.intel.com> References: <1519324923-196857-1-git-send-email-john.garry@huawei.com> <1519381801.10722.103.camel@linux.intel.com> <3c4c5f58-a661-13c8-cc1c-8d43828982cb@huawei.com> <1519407117.10722.124.camel@linux.intel.com> <88214a3e-82cc-c931-804c-7dc90fb8721f@huawei.com> <1519638828.10722.153.camel@linux.intel.com> <7221877b-a84a-63a1-ef86-1991f358df72@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <7221877b-a84a-63a1-ef86-1991f358df72@huawei.com> Sender: linux-kernel-owner@vger.kernel.org To: John Garry , gregkh@linuxfoundation.org, jslaby@suse.com, p.zabel@pengutronix.de, heiko@sntech.de, ed.blake@sondrel.com, jhogan@kernel.org Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@huawei.com List-Id: linux-serial@vger.kernel.org On Mon, 2018-02-26 at 10:45 +0000, John Garry wrote: > > > > > > > for supporting an 8250-compatible UART with > > > > > > > the following profile/features: > > > > > > > - platform device > > > > > > > - polling mode (i.e. no interrupt support) > > > > > > > - ACPI FW > > > > > > > > > > > > Elaborate this one, please. > > > > > > > > > > So we need to define our own HID here, and cannot use PNP > > > > > compatible > > > > > CID > > > > > (like PNP0501) as we cannot use the 8250 PNP driver. > > > > > > > > Why not? What are the impediments? > > > > > > > > > > To support the host controller for this device, we will create an > > > MFD, > > > i.e. platform device, per slave device. > > > > There is no answer here... > > > > > > > This is related to the Hisi LPC ACPI support, where we would > > > > > create > > > > > an > > > > > MFD (i.e. platform device) for the UART. > > > > > > > > Why you can't do properly in ACPI? > > > > No answer here either. > > > > Sorry, but with this level of communication it's no go for the > > series. > > > > Sorry if my answers did not tell you want you want to know. > > My point was that the 8250_pnp driver would be used for a pnp_device, > but we are creating a platform device for this UART slave so would > require a platform device driver, that which 8250_dw.c is. But I will > check on pnp device support. Perhaps it's not visible, though below is a description of the drivers we have: 8250_dw - OF/ACPI driver for Synopsys DW (+ DW DMA) 8250_lpss - PCI driver for Synopsys DW (+ DW DMA) 8250_of - generic 8250 compatible driver for OF 8250_pci - generic 8250 compatible driver for PCI 8250_pnp - generic 8250 compatible driver for ACPI 8250_* (except core parts) - custom glue drivers per some IPs By description you gave your driver fits 8250_pnp if ACPI tables crafted properly. Share the ACPI excerpt and we can discuss further how to improve them. -- Andy Shevchenko Intel Finland Oy