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Mon, 26 Feb 2018 06:28:42 -0500 Received: from mga06.intel.com ([134.134.136.31]:63292 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752377AbeBZL2l (ORCPT ); Mon, 26 Feb 2018 06:28:41 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,396,1515484800"; d="scan'208";a="20844176" Message-ID: <1519644517.10722.179.camel@linux.intel.com> Subject: Re: [RFC PATCH 0/2] serial: 8250_dw: IO space + polling mode support From: Andy Shevchenko 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 Date: Mon, 26 Feb 2018 13:28:37 +0200 In-Reply-To: <7221877b-a84a-63a1-ef86-1991f358df72@huawei.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> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.5-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-serial-owner@vger.kernel.org X-Mailing-List: linux-serial@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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