Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932563Ab3CTNYT (ORCPT ); Wed, 20 Mar 2013 09:24:19 -0400 Received: from mail-we0-f179.google.com ([74.125.82.179]:47241 "EHLO mail-we0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752078Ab3CTNYR (ORCPT ); Wed, 20 Mar 2013 09:24:17 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Wed, 20 Mar 2013 21:24:14 +0800 Message-ID: Subject: Re: [PATCH] usb host: Faraday FUSBH200 HCD driver. From: Yuan-Hsin Chen To: Alan Stern Cc: Felipe Balbi , gregkh@linuxfoundation.org, sarah.a.sharp@linux.intel.com, Julia.Lawall@lip6.fr, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Yuan-Hsin Chen , john453@faraday-tech.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2454 Lines: 71 Hi, On Tue, Mar 19, 2013 at 11:48 PM, Alan Stern wrote: > On Tue, 19 Mar 2013, Yuan-Hsin Chen wrote: > >> > What about the port_status registers? They're not between command and >> > async_next. If they aren't consistent with EHCI, it makes things a lot >> > more complicated. >> >> fusbh200 has only one port_status register with different offset, >> 0x30, and the position of some bits are different from EHCI. How about adding kernel configuration to adjust offset for FUSBH200 in ehci_def.h? So port_status would be in offset 0x20 from ehci_regs. For example, /* ASYNCLISTADDR: offset 0x18 */ u32 async_next; /* address of next async queue head */ #ifndef CONFIG_USB_EHCI_HCD_FUSBH200 u32 reserved1[2]; /* TXFILLTUNING: offset 0x24 */ u32 txfill_tuning; /* TX FIFO Tuning register */ #define TXFIFO_DEFAULT (8<<16) /* FIFO burst threshold 8 */ u32 reserved2[6]; /* CONFIGFLAG: offset 0x40 */ u32 configured_flag; #define FLAG_CF (1<<0) /* true: we'll support "high speed" */ #else u32 reserved1; #endif /* PORTSC: offset 0x44 */ u32 port_status[0]; /* up to N_PORTS */ Furthermore, there are PORT_POWER, PORT_OWNER, PORT_LED_XXX, PORT_TEST, PORT_WKCONN_E, PORT_WKDISC_E, PORT_WKOC_E absent in port_status of FUSBH200. Also PORT_OC and PORT_OCC are in another register. Is it ok to use quirk flag also? > > That's pretty nasty. Integrating that with the standard EHCI driver > would be considerably more difficult. > > Why was the FUSBH200 designed in this strange way? Why doesn't it use > the standard EHCI register layout? Were the engineers at Faraday > deliberately trying to make life harder for driver writers? > >> Also, usbmode_ex, hostpc, and txfill_tuning other than configured_flag >> are non-existent in fusbh200. They are used in both ehci-hcd.c and >> ehci-hub.c for several times. > > They are used only if the hardware supports them, that is, only if the > ehci->has_hostpc flag is set. > > Alan Stern > Thank you for your help. Yuan-Hsin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/