PXA3xx NAND Driver Questions

[Marcel Ziswiler <marcel@ziswiler.com>]

Hi there

Looking at drivers/mtd/nand/pxa3xx_nand.c lines 470 and 482 (see below) I
noticed that the sizes in the __raw_{read|write}sl() calls are left shifted by
two meaning multiplied by 4. Unfortunately I could not find an accurate
description of those __raw_{read|write}sl() calls, them being in ARM assembly I
assume they just read and write a block of IO memory. Now my first question:
Does this multiply by 4 really make sense? Aren't sizes usually specified in
bytes everywhere?

463 static int handle_data_pio(struct pxa3xx_nand_info *info)
464 {
465         int ret, timeout = CHIP_DELAY_TIMEOUT;
466
467         switch (info->state) {
468         case STATE_PIO_WRITING:
469                 __raw_writesl(info->mmio_base + NDDB, info->data_buff,
470                                 info->data_size << 2);
471
472                 enable_int(info, NDSR_CS0_BBD | NDSR_CS0_CMDD);
473
474                 ret = wait_for_completion_timeout(&info->cmd_complete,
 timeout);
475                 if (!ret) {
476                         printk(KERN_ERR "program command time out\n");
477                         return -1;
478                 }
479                 break;
480         case STATE_PIO_READING:
481                 __raw_readsl(info->mmio_base + NDDB, info->data_buff,
482                                 info->data_size << 2);
483                 break;
484         default:
485                 printk(KERN_ERR "%s: invalid state %d\n", __func__,
486                                 info->state);
487                 return -EINVAL;
488         }
489
490         info->state = STATE_READY;
491         return 0;
492 }

My second question is concerning operation without DMA. This currently seems to
be broken (e.g. if I load the module with use_dma set to 0, see below line 170)
it does not even recognize the NAND chip. Has anybody else tried this lately? It
worked just fine with the pre-mainline version using the manual {read,
write}_fifo_pio() calls.

170 static int use_dma = 1;
171 module_param(use_dma, bool, 0444);
172 MODULE_PARM_DESC(use_dma, "enable DMA for data transfering to/from NAND
 HW");

Cheers

Marcel