Re: [PATCH] sh7760mmc: host driver for SH7760 MMC interface

[Paul Mundt <lethal@linux-sh.org>]

On Thu, Jul 17, 2008 at 01:03:53PM +0200, Manuel Lauss wrote:
> Here is my latest attempt at an MMC host driver for the MMCIF interface
> found on many SH-4 socs, particularly the SH7760, SH778x, and SH7763.
> 
> This is a very basic driver, without DMA support and crippled performance
> due to hardware or driver bugs wrt. multiblock writes.
> 
> The driver has been extensively tested on SH7760 only.  The SH7780 and 7763
> MMCIF should theoretically work with some minor adjustments.
> 
> Patch is against latest linus git.
> 
Looks good to me in general, though a few minor nits.

> +/* The MMCIF does not provide any facilities for card- and read-only
> + * detection as well as voltage setting. Use GPIOs in the board-specific
> + * code for that. PLEASE READ Documentation/sh/sh7760-mmc.txt if you
> + * want to use this driver with your board!
> + *
This document appears to be missing in your patch.

> +static inline unsigned short MMC_INW(struct shmmc_host *h, unsigned int reg)
> +{
> +	return ioread16(h->iobase + reg);
> +}
> +
> +static inline void MMC_OUTW(struct shmmc_host *h, int reg, unsigned short val)
> +{
> +	iowrite16(val, h->iobase + reg);
> +}
> +
> +static inline unsigned char MMC_INB(struct shmmc_host *h, unsigned int reg)
> +{
> +	return ioread8(h->iobase + reg);
> +}
> +
> +static inline void MMC_OUTB(struct shmmc_host *h, int reg, unsigned char val)
> +{
> +	iowrite8(val, h->iobase + reg);
> +}
> +
These accessors seem pretty pointless, any reason you don't just use
ioread/writeX() directly?

> +static void shmmc_done_tasklet(unsigned long arg)
> +{
> +	struct shmmc_host *host = (struct shmmc_host *)arg;
> +	struct mmc_request *mrq;
> +
> +	mrq = host->mrq;
> +
> +	/* should not happen, but I've seen it once or twice */
> +	if (!mrq) {
> +		pr_debug("%s: mrq = 0!\n", mmc_hostname(host->mmc));
> +		return;
> +	}
> +	host->mrq = NULL;
> +
> +	/* HACK ALERT: I need this cache flush on my SH7760 system because
> +	 * otherwise bits of the card response will be corrupted,
> +	 * preventing card identification due to malformed CID/SCR/...
> +	 * Don't know why, but it has been this way all the way back to
> +	 * 2.6.17.  -- mlau
> +	 */
> +	flush_dcache_all();
> +
flush_dcache_all() seems a bit heavy-handed, even for a hack. Though it
would be good to know why this is occuring in the first place..

Also, is the implication that you didn't need this in 2.6.16 and earlier,
or that 2.6.17 was the first kernel you tested this driver on?

> +static void shmmc_data_done(struct shmmc_host *host)

Also, is the implication that you didn't need this in 2.6.16 and earlier,
or that 2.6.17 was the first kernel you tested this driver on?

> +static inline void
> +shmmc_write_fifo(struct shmmc_host *host, unsigned long cnt)
> +{
> +	unsigned short *sga;
> +
> +	/* get a pointer to physical RAM */
> +	sga = (unsigned short *)P2SEGADDR(sg_dma_address(host->data->sg)
> +					  + host->xfered);
> +
P2SEGADDR is going away in the future completely, so it would be
preferable not to opencode more instances of it in new code.

> +	host->ioarea = request_mem_region(r->start, r->end - r->start + 1,
> +					  dev->name);
> +	if (!host->ioarea)
> +		goto out0;
> +
> +	host->iobase = ioremap(r->start, r->end - r->start + 1);
> +	if (!host->iobase)
> +		goto out1;
> +
Off-by-1 on resource size. request_mem_region() wants r->end - r->start
while ioremap wants the + 1.

> +MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");
> +MODULE_DESCRIPTION("SH7760 MMCIF driver");
> +MODULE_LICENSE("GPL");

Your boilerplate at the top suggests v2 only, while MODULE_LICENSE("GPL")
implies "or any later version". You may want to revise this to be "GPL
v2" if restricting it is indeed your intention.