Messages in this thread | | | Date | Sun, 1 Feb 2009 19:54:35 +0100 | From | Michał Mirosław <> | Subject | Re: RFC: Driver for CB710/720 memory card reader (MMC part) - v3 |
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Hello again,
Sorry for a long delay with my reply.
On Fri, Nov 14, 2008 at 10:06:58PM +0100, Pierre Ossman wrote: > On Wed, 29 Oct 2008 15:11:47 +0100 > Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote: > > Here is the driver for CB710 SD/MMC reader updated to recently released > > kernel version 2.6.27. The code is divided into PCI device driver > > (wrapped that registers three platform devices) and MMC reader driver. > > This idea was taken from TIFM driver. > > > > Changes from v2: > > - return EINVAL for unsupported data transfer sizes > > - use sg_mapping_iter for PIO from/to scatterlist > > - add slot release function and prevent kobject leak on device registration's > > error path > > > > If this code looks reasonably good, then I'll post patches against the > > real kernel tree. The file distribution plan is: > It looks more or less good to go. I have some small notes, and you > probably need to poke some scatterlist folks to okay those changes > (should probably be a separate patch).
There's no entry in MAINTAINERS list, but I assume it's Jens Axboe as he's in the copyright section in scatterlist.c.
> > +/* slot port accessors - in case it turns out inX() is all that is needed */ > > +#define CB710_PORT_ACCESSORS(t) \ > > +static inline void cb710_write_port_##t(struct cb710_slot *slot, \ > > + unsigned port, u##t value) \ > > +{ \ > > + iowrite##t(value, slot->iobase + port); \ > > +} \ > > + \ > > +static inline u##t cb710_read_port_##t(struct cb710_slot *slot, \ > > + unsigned port) \ > > +{ \ > > + return ioread##t(slot->iobase + port); \ > > +} \ > > + \ > > +static inline void cb710_modify_port_##t(struct cb710_slot *slot, \ > > + unsigned port, u##t set, u##t clear) \ > > +{ \ > > + iowrite##t( \ > > + (ioread##t(slot->iobase + port) & ~clear)|set, \ > > + slot->iobase + port); \ > > +} > > + > > +CB710_PORT_ACCESSORS(8) > > +CB710_PORT_ACCESSORS(16) > > +CB710_PORT_ACCESSORS(32) > This is clearer than what you had before, but I still think you should > consider using the kernel functions directly.
The really useful one here is cb710_modify_port_*(), read/write are for consistency. I'd prefer to keep those wrappers because they help to eliminate some noise from register access logic in the driver.
> > +/* helper functions */ > > + > > +static inline void cb710_set_irq_handler(struct cb710_slot *slot, > > + cb710_irq_handler_t handler) > > +{ > > + rcu_assign_pointer(slot->irq_handler, handler); > > + synchronize_rcu(); /* sync to IRQ handler */ > > +} > Why RCU:s? This smells of premature optimisation.
I thought this as the easiest way to assure that on return from cb710_set_irq_handler() there's no interrupt handler running using the old slot->irq_handler value.
> > +/* per-MMC-reader structure */ > > +struct cb710_mmc_reader { > > + struct tasklet_struct finish_req_tasklet; > > + struct mmc_request *mrq; > > + spinlock_t irq_lock; > > + unsigned char last_power_mode; > > +#ifdef VERBOSE_DEBUG > > + spinlock_t serialization_lock; > > + unsigned char active_req, active_ios; > > +#endif > > +}; > I couldn't find VERBOSE_DEBUG defined somewhere. For ease of use with > future testers, you should connect it to some Kconfig option.
This is mostly related to veryfying some assumptions on the MMC core infrastructure. I can remove this altogether if the calls to driver ->request() and ->set_ios() are really guaranteed to be serialized.
> > +static int cb710_suspend(struct pci_dev *pdev, pm_message_t state) > > +{ > > + pci_save_state(pdev); > > + pci_disable_device(pdev); > > + if (state.event & PM_EVENT_SLEEP) > > + pci_set_power_state(pdev, PCI_D3cold); > > + return 0; > > +} > > + > > +static int cb710_resume(struct pci_dev *pdev) > > +{ > > + pci_set_power_state(pdev, PCI_D0); > > + pci_restore_state(pdev); > > + return pcim_enable_device(pdev); > > +} > Free/restore interrupt?
Hmm. I checked couple random drivers in kernel tree and none (including MMC host drivers) are touching interrupt allocation in suspend/resume.
> > +#if 0 > > + /* original driver set bit 14 for MMC/SD application > > + * commands. There's no difference 'on the wire' and > > + * it apparently works without it anyway. > > + */ > > + if (flags & MMC_CMD_IS_APPCMD) > > + cb_flags |= 0x4000; > > +#endif > As this code is just useless, please clean it out before you submit the > driver.
Will turn this into pure comment - just to remember.
> > + mmc->ops = &cb710_mmc_host; > > + mmc->f_max = val; > > + mmc->f_min = val >> cb710_clock_divider_log2[CB710_MAX_DIVIDER_IDX]; > > + mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34|MMC_VDD_34_35; > Since you can't change the voltage, this seems wrong. My guess is that > the MMC_VDD_34_35 define should go.
That's what the original driver advertises. I can't verify the exact voltage that is supplied to the card, so I'll assume that's 3.3V and remove MMC_VDD_34_35 as you suggest.
> > +static int __devexit cb710_mmc_exit(struct platform_device *pdev) > > +{ > > + struct cb710_slot *slot = cb710_pdev_to_slot(pdev); > > + struct mmc_host *mmc = cb710_slot_to_mmc(slot); > > + struct cb710_mmc_reader *reader = mmc_priv(mmc); > > + > > + mmc_remove_host(mmc); > > + > > + /* XXX what if IRQ arrives now? */ > > Most drivers handle this by sticking their head in the sand, but the > proper way is probably to disable the card insertions interrupt before > mmc_remove_host(). > (and there should be no other unsolicited interrupts)
Will try.
Best Regards, Michał Mirosław
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