Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932970Ab1DMVDR (ORCPT ); Wed, 13 Apr 2011 17:03:17 -0400 Received: from kroah.org ([198.145.64.141]:59884 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932935Ab1DMVDP (ORCPT ); Wed, 13 Apr 2011 17:03:15 -0400 Date: Wed, 13 Apr 2011 14:02:38 -0700 From: Greg KH To: =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: linux-wireless@vger.kernel.org, "John W. Linville" , b43-dev@lists.infradead.org, Michael =?iso-8859-1?Q?B=FCsch?= , Larry Finger , George Kashperko , Arend van Spriel , linux-arm-kernel@lists.infradead.org, Russell King , Arnd Bergmann , Andy Botting , linuxdriverproject , "linux-kernel@vger.kernel.org" Subject: Re: [RFC][PATCH V4] axi: add AXI bus driver Message-ID: <20110413210238.GB7523@kroah.com> References: <1302634375-2378-1-git-send-email-zajec5@gmail.com> <20110413163113.GA24015@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4593 Lines: 131 On Wed, Apr 13, 2011 at 09:39:54PM +0200, Rafał Miłecki wrote: > 2011/4/13 Greg KH : > >> diff --git a/drivers/axi/axi_pci_bridge.c b/drivers/axi/axi_pci_bridge.c > >> new file mode 100644 > >> index 0000000..17e882c > >> --- /dev/null > >> +++ b/drivers/axi/axi_pci_bridge.c > >> @@ -0,0 +1,33 @@ > >> +/* > >> + * AXI PCI bridge module > >> + * > >> + * Licensed under the GNU/GPL. See COPYING for details. > >> + */ > >> + > >> +#include "axi_private.h" > >> + > >> +#include > >> +#include > >> + > >> +static DEFINE_PCI_DEVICE_TABLE(axi_pci_bridge_tbl) = { > >> +     { PCI_DEVICE(PCI_VENDOR_ID_BROADCOM, 0x4331) }, > >> +     { PCI_DEVICE(PCI_VENDOR_ID_BROADCOM, 0x4353) }, > >> +     { PCI_DEVICE(PCI_VENDOR_ID_BROADCOM, 0x4727) }, > >> +     { 0, }, > >> +}; > >> +MODULE_DEVICE_TABLE(pci, axi_pci_bridge_tbl); > >> + > >> +static struct pci_driver axi_pci_bridge_driver = { > >> +     .name = "axi-pci-bridge", > >> +     .id_table = axi_pci_bridge_tbl, > >> +}; > >> + > >> +int __init axi_pci_bridge_init(void) > >> +{ > >> +     return axi_host_pci_register(&axi_pci_bridge_driver); > >> +} > >> + > >> +void __exit axi_pci_bridge_exit(void) > >> +{ > >> +     axi_host_pci_unregister(&axi_pci_bridge_driver); > >> +} > > > > You register a pci driver that does nothing?  That's not right, you need > > to then base your axi bus off of that pci device, so it is hooked up > > correctly in the /sys/devices/ tree.  Otherwise you are somewhere up in > > the virtual location for your axi bus, right? > > Please take a look at: > driver->probe = axi_host_pci_probe; > driver->remove = axi_host_pci_remove; > return pci_register_driver(driver); Odd, why not just set up those functions in that file? Or move all of this to that file and do it there? This seems like a very small file :) > >> +bool axi_core_is_enabled(struct axi_device *core) > >> +{ > >> +     if ((axi_aread32(core, AXI_IOCTL) & (AXI_IOCTL_CLK | AXI_IOCTL_FGC)) > >> +         != AXI_IOCTL_CLK) > >> +             return false; > >> +     if (axi_aread32(core, AXI_RESET_CTL) & AXI_RESET_CTL_RESET) > >> +             return false; > >> +     return true; > >> +} > >> +EXPORT_SYMBOL(axi_core_is_enabled); > > > > EXPORT_SYMBOL_GPL()? > > > > What module uses this?  And why would it care? > > > >> +EXPORT_SYMBOL(axi_core_enable); > > > > EXPORT_SYMBOL_GPL()? > > > > Same goes for your other exports, just want you to be sure here. > > Hm, I'm not sure. Using EXPORT_SYMBOL_GPL will forbid closed source > drivers from using our bus driver, right? I'm don't have preferences > on this, if you prefer us to force GPL, I can. It's totally up to you, it's your code, not mine. Just wanted to remind you of the option. > >> +u32 xaxi_chipco_gpio_control(struct axi_drv_cc *cc, u32 mask, u32 value) > >> +{ > >> +     return axi_cc_write32_masked(cc, AXI_CC_GPIOCTL, mask, value); > >> +} > >> +EXPORT_SYMBOL(xaxi_chipco_gpio_control); > > > > "xaxi"?  Shouldn't that be consistant with the other exports and start > > with "axi"? > > Left from old tests/rewrites/splitting. Thanks. > > > >> +static u8 axi_host_pci_read8(struct axi_device *core, u16 offset) > >> +{ > >> +     if (unlikely(core->bus->mapped_core != core)) > > > > Are you sure about the use of unlikely in this, and other functions? > > The compiler almost always does a better job than we do for these types > > of calls, just let it do it's job. > > > >> +             axi_host_pci_switch_core(core); > >> +     return ioread8(core->bus->mmio + offset); > > > > I think because of that unlikely, you just slowed down all pci devices, > > right?  That's not very nice :) > > Hm, my logic suggests it is alright, but please consider this once > more with me ;) > > For the most of the time mapped_core (active core) do not change. We > perform few hundreds of operations on one core in a row. This way > mapped_core points to passed core for most of the time. Condition > (mapped_core != core) is unlikely to happen. > > Is there anything wrong in my logic? Drivers almost _never_ need to use likely or unlikely in their code. The CPU can schedule things better and so can the compiler, so I would just drop them, _unless_ you can show a benchmark where it matters. thanks, greg k-h -- 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/