From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ondrej Zary Subject: Re: [PATCH 4/6] g_NCR5380: Add IRQ auto-configuration for HP C2502 Date: Thu, 3 Nov 2016 09:00:56 +0100 Message-ID: <201611030900.56371.linux@rainbow-software.org> References: <1477945112-25659-1-git-send-email-linux@rainbow-software.org> <201611020929.22464.linux@rainbow-software.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Finn Thain Cc: Christoph Hellwig , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-scsi@vger.kernel.org On Thursday 03 November 2016, Finn Thain wrote: > On Wed, 2 Nov 2016, Ondrej Zary wrote: > > > Also, you've ignored the irq module parameters. From the user's point > > > of view, surely the least surprising thing is to attempt to configure > > > the card for whatever irq the user asked for. > > > > I haven't. NCR5380_find_irq is only called when irq is set to IRQ_AUTO. > > My mistake. > > > > If the specified irq isn't supported by the board, just log an error > > > and fail. If you want to be user friendly, print a message to tell > > > them what irqs the card supports. > > > > If the IRQ is not supported (or does not work), user gets a warning and > > the driver continues with IRQ disabled. > > > > > If the user asks for IRQ_AUTO, just configure the board for a > > > hard-coded default, say 9, and print a warning message to say so. > > > > The card is almost Plug&Play. The base address is already configured > > automatically by the driver so doing the same for IRQ makes sense. > > Why don't we see any other drivers doing this? Many ISA sound card drivers do this - there's even a function for this: static int snd_legacy_find_free_irq(int *irq_table) Unfortunately, it's defined in ALSA headers and even protected with an #ifdef. > If the card was really plug and play, I expect we would just call > pnp_irq(), as the other PNP drivers do. The card predates the PnP standard so we can't. > > > Either way, if request_irq fails just continue with NO_IRQ, as per > > > usual. > > > > > > To me that's the most flexible and least surprising behaviour. But > > > again, if someone with more ISA knowledge wishes to weigh in, that's > > > fine too. -- Ondrej Zary