On Thu, Jun 4, 2009 at 8:58 PM, Tony Lindgren<tony@xxxxxxxxxxx> wrote: > * vimal singh <vimalsingh@xxxxxx> [090604 02:34]: >> On Wed, Jun 3, 2009 at 10:03 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: >> > * Singh, Vimal >> <IMCEAEX-_O=TI_OU=BD_CN=RECIPIENTS_CN=X0094262@xxxxxxxxxxxxxxxxx> [090602 >> 23:46]: >> >> >> >> On Wed, Jun 3, 2009 at 2:06 AM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: >> >> > * vimal singh <vimalsingh@xxxxxx> [090602 05:40]: >> >> >> This patch adds prefetch support to access nand flash in both mpu and dma >> mode. >> >> >> This patch also adds 8-bit nand support (omap_read/write_buf8). >> >> >> Prefetch can be used for both 8- and 16-bit devices. >> >> > >> >> > This should be reviewed on the linux-omap@xxxxxxxxxxxxxxx list for sure. >> >> > One other comment below. >> >> > >> >> >> Signed-off-by: Vimal Singh <vimalsingh@xxxxxx> >> >> >> --- >> >> >> I prepared this patch on top of "OMAP2 / OMAP3 NAND driver" patch: >> >> >> http://lists.infradead.org/pipermail/linux-mtd/2009-May/025562.html >> >> >> >> >> >> --- >> >> >> arch/arm/mach-omap2/gpmc.c | 102 ++++++++++ >> >> >> arch/arm/plat-omap/include/mach/gpmc.h | 4 >> >> >> drivers/mtd/nand/Kconfig | 17 + >> >> >> drivers/mtd/nand/omap2.c | 308 >> ++++++++++++++++++++++++++++++++- >> >> >> 4 files changed, 422 insertions(+), 9 deletions(-) >> >> >> >> >> >> Index: mtd-2.6/arch/arm/mach-omap2/gpmc.c >> >> >> =================================================================== >> >> >> --- mtd-2.6.orig/arch/arm/mach-omap2/gpmc.c >> >> >> +++ mtd-2.6/arch/arm/mach-omap2/gpmc.c >> >> >> @@ -54,6 +54,12 @@ >> >> >> #define GPMC_CHUNK_SHIFT 24 /* 16 MB */ >> >> >> #define GPMC_SECTION_SHIFT 28 /* 128 MB */ >> >> >> >> >> >> +#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH >> >> >> +#define CS_NUM_SHIFT 24 >> >> >> +#define ENABLE_PREFETCH 7 >> >> >> +#define DMA_MPU_MODE 2 >> >> >> +#endif >> >> >> + >> >> >> static struct resource gpmc_mem_root; >> >> >> static struct resource gpmc_cs_mem[GPMC_CS_NUM]; >> >> >> static DEFINE_SPINLOCK(gpmc_mem_lock); >> >> >> @@ -383,6 +389,99 @@ void gpmc_cs_free(int cs) >> >> >> } >> >> >> EXPORT_SYMBOL(gpmc_cs_free); >> >> >> >> >> >> +#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH >> >> >> +/** >> >> >> + * gpmc_prefetch_init - configures default configuration for prefetch >> engine >> >> >> + */ >> >> >> +static void gpmc_prefetch_init(void) >> >> >> +{ >> >> >> + /* Setting the default threshold to 64 */ >> >> >> + gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0); >> >> >> + gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x40 << 8); >> >> >> + gpmc_write_reg(GPMC_PREFETCH_CONFIG2, 0x0); >> >> >> +} >> >> > >> >> > Why would you want to have NAND specific init code int gpmc.c? >> >> > >> >> > The purpose if gpmc.c is to provide access to configuring the >> >> > General Purpose Memory Controller (GPMC). You should just provide >> >> > functions in gpmc.c for the platform init code to use, and then >> >> > the drivers can stay platform independent. >> >> >> >> In my understanding, this 'prefetch' engine is part of GPMC itself, it is a >> >> kind of feature provided by GPMC which can be utilized by NAND driver. >> >> So, to me, it makes sens to get initialized prefetch by GPMC itself so that >> >> NAND driver can use it. >> > >> > But it should not have a dependency to NAND. >> >> This engine, in GPMC, is dedicated for NAND devices only. >> >> > >> >> Another reason was that all read / write to GPMC register are done by >> >> functions 'gpmc_read_reg' / 'gpmc_write_reg', which have been made >> >> 'static' in nature. >> > >> > That's why you need to provide a generic function in gpmc.c to enable >> > prefetch that the platform code for any driver can use. >> >> Exactly, and whenever a platform code uses gpmc init call, gpmc initializes >> this engine too. Since prefetch engine is the part of GPMC, IMHOP, it should >> get initialized as part of GPMC initialization. > > No, the driver needing it should initialize it. There should not be any > ifdefs needed in the gpmc.c for that. Are you suggesting to move gpmc prefetch specific code to 'drivers/mtd/nand/omap2.c'? This can be done but then, we will be accessing gpmc registers outside gpmc.c. Is that ok? > >> And then there are prefetch start, stop and status functions calls have been >> provided to be used by NAND driver. > > These should really be done in the platform init code for the NAND driver. > The NAND driver really should be generic, not omap specific. Are you talking about different omap versions or omap itself, I am bit confused. This NAND driver is omap specific only. -Vimal > Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
