linux-kernel - Re: [PATCH v2] pcmcia: export pcmcia_bus

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Message-ID: <20070513235128.GA25128@lixom.net>
Date:	Sun, 13 May 2007 18:51:28 -0500
From:	olof@...om.net (Olof Johansson)
To:	Christoph Hellwig <hch@...radead.org>,
	linux-pcmcia@...ts.infradead.org, akpm@...l.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] pcmcia: export pcmcia_bus_type

Hi,

On Mon, May 14, 2007 at 12:10:29AM +0100, Russell King wrote:
> Some random review comments on your driver, while I was passing.  Spotted
> a few things.

Thanks, I appreciate the feedback.

> On Sun, May 13, 2007 at 04:40:07PM -0500, Olof Johansson wrote:
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/sched.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/platform_device.h>
> 
> Silly duplicate includes.

Silly indeed.

> > +#include <linux/errno.h>
> > +#include <linux/init.h>
> > +#include <linux/delay.h>
> > +#include <linux/interrupt.h>
> > +
> > +#include <pcmcia/ss.h>
> > +#include <asm/of_platform.h>
> > +
> > +static const char driver_name[] = "electra-cf";
> >...
> > +static int electra_cf_get_status(struct pcmcia_socket *s, u_int *sp)
> > +{
> > +	struct electra_cf_socket *cf;
> > +
> > +	if (!sp)
> > +		return -EINVAL;
> 
> Never called with a NULL argument, so useless check.

Ok. Carried over from omap_cf, but I'll definitely fix it here.

> > +
> > +	cf = container_of(s, struct electra_cf_socket, socket);
> > +
> > +	/* NOTE CF is always 3VCARD */
> > +	if (electra_cf_present(cf)) {
> > +		struct electra_cf_socket *cf;
> > +
> > +		*sp = SS_READY | SS_DETECT | SS_POWERON | SS_3VCARD;
> > +		cf = container_of(s, struct electra_cf_socket, socket);
> > +		s->pci_irq = cf->irq;
> > +	} else
> > +		*sp = 0;
> > +	return 0;
> > +}
> >...
> > +static int electra_cf_ss_suspend(struct pcmcia_socket *s)
> > +{
> > +	pr_debug("%s: %s\n", driver_name, __FUNCTION__);
> > +	return electra_cf_set_socket(s, &dead_socket);
> > +}
> 
> That's already done for you.  Remove this function entirely and set
> the ".suspend" method to NULL.

Thanks, will do.

> 
> > +static int electra_cf_set_io_map(struct pcmcia_socket *s,
> > +				 struct pccard_io_map *io)
> > +{
> > +	struct electra_cf_socket *cf;
> > +
> > +	cf = container_of(s, struct electra_cf_socket, socket);
> > +	io->flags &= MAP_ACTIVE|MAP_ATTRIB|MAP_16BIT;
> > +	io->start = (unsigned long)cf->io_base;
> > +	io->stop = (unsigned long)cf->io_base + 0x800 - 1;
> > +	return 0;
> > +}
> 
> PCMCIA code will ignore your writes to 'io'.  Therefore, does this
> do anything useful?  If not, an empty function will do.

Not sure if it does, it came over from omap_cf with some modifications
by me.  I'll take a closer look when I rework the rest of the I/O
mapping stuff.

> > +	cf->socket.owner = THIS_MODULE;
> > +	cf->socket.dev.parent = &ofdev->dev;
> > +	cf->socket.ops = &electra_cf_ops;
> > +	cf->socket.resource_ops = &pccard_static_ops;
> > +	cf->socket.features = SS_CAP_PCCARD | SS_CAP_STATIC_MAP |
> > +				SS_CAP_MEM_ALIGN;
> > +	cf->socket.map_size = 0x800;
> > +	cf->socket.io[0].res = &cf->iomem;
> 
> Not a good idea - PCMCIA manages this resources itself and will free it
> when the card is removed.  Use ss_cap_static_map and socket.io_offset.

Right, I'm going to rework those parts alltogether.

> > +static int __devexit electra_cf_remove(struct of_device *ofdev)
> > +{
> > +	struct device *device = &ofdev->dev;
> > +	struct electra_cf_socket *cf;
> > +
> > +	cf = dev_get_drvdata(device);
> > +
> > +	cf->active = 0;
> > +	pcmcia_unregister_socket(&cf->socket);
> > +	del_timer_sync(&cf->timer);
> > +	free_irq(cf->irq, cf);
> 
> What if an IRQ occurs after the timer has been deleted?  Doesn't the
> interrupt handler re-add the timer back?

Ah, yes, good point.


Thanks,

-Olof
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