[PATCH RESEND v4 1/4] omap3: nand: prefetch in irq mode support

[Ghorai, Sukumar]

Tony,

> -----Original Message-----
> From: linux-omap-owner at vger.kernel.org [mailto:linux-omap-
> owner at vger.kernel.org] On Behalf Of Ghorai, Sukumar
> Sent: Monday, September 20, 2010 7:01 PM
> To: Tony Lindgren
> Cc: linux-omap at vger.kernel.org; linux-mtd at lists.infradead.org; linux-arm-
> kernel at lists.infradead.org
> Subject: RE: [PATCH RESEND v4 1/4] omap3: nand: prefetch in irq mode
> support
> 
> Tony,
> 
> > -----Original Message-----
> > From: Ghorai, Sukumar
> > Sent: Saturday, September 18, 2010 11:55 PM
> > To: 'Tony Lindgren'
> > Cc: 'linux-omap at vger.kernel.org'; 'linux-mtd at lists.infradead.org';
> 'linux-
> > arm-kernel at lists.infradead.org'
> > Subject: RE: [PATCH RESEND v4 1/4] omap3: nand: prefetch in irq mode
> > support
> >
> > Tony,
> >
> > > -----Original Message-----
> > > From: Tony Lindgren [mailto:tony at atomide.com]
> > > Sent: Friday, September 17, 2010 11:25 PM
> > > To: Ghorai, Sukumar
> > > Cc: linux-omap at vger.kernel.org; linux-mtd at lists.infradead.org; linux-
> > arm-
> > > kernel at lists.infradead.org; Vimal Singh
> > > Subject: Re: [PATCH RESEND v4 1/4] omap3: nand: prefetch in irq mode
> > > support
> > >
> > > * Sukumar Ghorai <s-ghorai at ti.com> [100916 00:53]:
> > > > This patch enable prefetch-irq mode for NAND.
> > > >
> > > > --- a/drivers/mtd/nand/omap2.c
> > > > +++ b/drivers/mtd/nand/omap2.c
> > > > @@ -467,6 +485,152 @@ static void omap_write_buf_dma_pref(struct
> > > mtd_info *mtd,
> > > >  		omap_nand_dma_transfer(mtd, (u_char *) buf, len, 0x1);
> > > >  }
> > > >
> > > > +/*
> > > > + * omap_nand_irq - GMPC irq handler
> > > > + * @this_irq: gpmc irq number
> > > > + * @dev: omap_nand_info structure pointer is passed here
> > > > + */
> > > > +static irqreturn_t omap_nand_irq(int this_irq, void *dev)
> > > > +{
> > > > +	struct omap_nand_info *info = (struct omap_nand_info *) dev;
> > > > +	u32 bytes;
> > > > +	u32 irq_stat;
> > > > +
> > > > +	irq_stat = gpmc_read_status(GPMC_GET_IRQ_STATUS);
> > > > +	bytes = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
> > > > +	bytes = bytes  & 0xFFFC; /* io in multiple of 4 bytes */
> > > > +	if (info->iomode == OMAP_NAND_IO_WRITE) { /* checks for write
> io */
> > > > +		if (irq_stat & 0x2)
> > > > +			goto done;
> > > > +
> > > > +		if (info->buf_len & (info->buf_len < bytes))
> > > > +			bytes = info->buf_len;
> > > > +		else if (!info->buf_len)
> > > > +			bytes = 0;
> > > > +		iowrite32_rep(info->nand.IO_ADDR_W,
> > > > +						(u32 *)info->buf, bytes >> 2);
> > > > +		info->buf = info->buf + bytes;
> > > > +		info->buf_len -= bytes;
> > > > +
> > > > +	} else {
> > > > +		ioread32_rep(info->nand.IO_ADDR_R,
> > > > +						(u32 *)info->buf, bytes >> 2);
> > > > +		info->buf = info->buf + bytes;
> > > > +
> > > > +		if (irq_stat & 0x2)
> > > > +			goto done;
> > > > +	}
> > > > +	gpmc_cs_configure(info->gpmc_cs, GPMC_SET_IRQ_STATUS,
> irq_stat);
> > > > +	irq_stat = gpmc_read_status(GPMC_GET_IRQ_STATUS);
> > > > +
> > > > +	return IRQ_HANDLED;
> > > > +
> > > > +done:
> > > > +	complete(&info->comp);
> > > > +	/* disable irq */
> > > > +	gpmc_cs_configure(info->gpmc_cs, GPMC_ENABLE_IRQ, 0);
> > > > +
> > > > +	/* clear status */
> > > > +	gpmc_cs_configure(info->gpmc_cs, GPMC_SET_IRQ_STATUS,
> irq_stat);
> > > > +	irq_stat = gpmc_read_status(GPMC_GET_IRQ_STATUS);
> > > > +
> > > > +	return IRQ_HANDLED;
> > > > +}
> > >
> > > This handler should be in gpmc.c as it may be needed for other GPMC
> > > connected devices on the same system. You can use chained irq handlers
> > > to allow all the drivers to use the interrupt then.
> >
> > [Ghorai]
> > You mean as this function used the gpmc-irq number in nand file, so
> > handler should move to gpmc.c file?
> > 	1. For that we need to add one io-struct (to keep io buffer status)
> > in gpmc.c;
> >
> > 	2. Also need help how to sync between gpmc.c/omap_nand_irq() and
> > omap2.c/omap_write_buf_irq_pref(), men how read/write function know that
> > work done in interrupt-context? Or you prefer to move the complete IO
> > function (omap_read/write_buf_irq_pref) to gpmc.c?
> >
> > 	3. gpmc does not now about the read and write address that's
> > applicable for NAND. So how to pass the IO address from omap2.c to
> gpmc.c,
> > interrupt handler?
> >
> >
> > So, please let me know your suggestion again such that I can post this
> > time itself. Otherwise again it will miss from coming release, this was
> > posted/reviewed for last release too. And suggest to void repeating of
> > missing release window again.
> 
> [Ghorai] Please reply with your 2nd suggestion.
[Ghorai] Please reply with your 2nd suggestion.

> >
> > >
> > > Regards,
> > >
> > > Tony
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