From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752420Ab3GXJwJ (ORCPT ); Wed, 24 Jul 2013 05:52:09 -0400 Received: from mail.free-electrons.com ([94.23.35.102]:54136 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752308Ab3GXJwF (ORCPT ); Wed, 24 Jul 2013 05:52:05 -0400 Date: Wed, 24 Jul 2013 11:51:45 +0200 From: Maxime Ripard To: Geert Uytterhoeven Cc: Axel Lin , Thomas Gleixner , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RFT] irqchip: sun4i: Remove wrong irq_ack callback implementation Message-ID: <20130724095145.GK10389@lukather> References: <1373121329.13289.2.camel@phoenix> <20130711161353.GV11243@lukather> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="EMQjp+MvU6EBGjHc" Content-Disposition: inline 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 --EMQjp+MvU6EBGjHc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Geert, On Fri, Jul 19, 2013 at 11:29:30AM +0200, Geert Uytterhoeven wrote: > On Thu, Jul 11, 2013 at 6:13 PM, Maxime Ripard > wrote: > > On Sat, Jul 06, 2013 at 10:35:29PM +0800, Axel Lin wrote: > >> According to the datasheet[1], the Interrupt IRQ Pending Registers are > >> read-only. The implementation of sun4i_irq_ack() looks wrong because i= t writes > >> to these read-only registers. > > > > Right, but the datasheet also says that these registers are "clear" > > register, which might indicate that it's actually R/W. >=20 > I guess it means that the flags are cleared automatically on read? > That's not so uncommon for interrupt pending registers. My understanding in this case is that the pending register is just a "copy" of the pending bits in the related hardware IP, so that clearing it in the interrupt controller won't do much, since it will be re-set just after the clear, while if you do clear the interrupt bit in the IP, it will clear it automatically in the interrupt controller. Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com --EMQjp+MvU6EBGjHc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJR76OxAAoJEBx+YmzsjxAgLwYP/jsfhqGxgyH0a6ii5U7Li6Fp f4qbD8XWYc3S9P4ecns7MIWR69LhcbpMPc6rdqHi3ukhXu/FPUrEQP5BQmwqiB0H HYnRjZwawGgDwT55ztRYSZAZrKY3DvOYtmvTreyZgg0TJNmy26cEFPnOyGn7IvgA xyF4iM8GUvlrONswU6B/5tCQPLB2iN3DI6pFJ02MKQp+SaD0/aQjxiCTaOu8aSaP Yg0+erc8Cb7phKBjvcYQgB0RVkdnPbUxNLm8MhSdRhK63TR/vyDplwIsJv80f3hY qsnk1rv+7AH0vvTaZrycDiIJ1wbgLQKuvm8EBQ/Js/l8E/bKXDnzuZpgZk7XMhip zmlReoAl5oqsi9EsKofelD//BQ+g0R0EwfXCN4Dhkp2NvKxtR19djNnWfljbYl21 YhO4v2jEQnkBoVE3+/l3aWa1c8zmN+2w35Ibs5FnLqKseipmiJPWiNhTeVpPaFOa xcmkk/BHYwM5jt9x3djmhVUpH3o+ruGIQRH6UKRiSctMuR+0v83gsNN7RrnuEGQk 7jkHIu5qfEFvmxv8Zr0afZ1RWSDnflaFlhKd5TbtvnqsuSj4IzihAKDIH9KHOV55 r/mSOSxOFEpKx5yMzI+iTgj27dDTGmLBWewbyX43O9nPlfJtlD92PtCZWJqNPVYT bpxy6rTK/lt9gQw71hlU =+gt5 -----END PGP SIGNATURE----- --EMQjp+MvU6EBGjHc--