diff options
| -rw-r--r-- | drivers/mmc/host/alcor.c | 54 | ||||
| -rw-r--r-- | include/linux/alcor_pci.h | 2 |
2 files changed, 37 insertions, 19 deletions
diff --git a/drivers/mmc/host/alcor.c b/drivers/mmc/host/alcor.c index 3e2efbf3cf8c..4b2690756453 100644 --- a/drivers/mmc/host/alcor.c +++ b/drivers/mmc/host/alcor.c @@ -117,6 +117,9 @@ static void alcor_reset(struct alcor_sdmmc_host *host, u8 val) dev_err(host->dev, "%s: timeout\n", __func__); } +/* + * Perform DMA I/O of a single page. + */ static void alcor_data_set_dma(struct alcor_sdmmc_host *host) { struct alcor_pci_priv *priv = host->alcor_pci; @@ -153,12 +156,26 @@ static void alcor_trigger_data_transfer(struct alcor_sdmmc_host *host) ctrl |= AU6601_DATA_WRITE; if (data->host_cookie == COOKIE_MAPPED) { + /* + * For DMA transfers, this function is called just once, + * at the start of the operation. The hardware can only + * perform DMA I/O on a single page at a time, so here + * we kick off the transfer with the first page, and expect + * subsequent pages to be transferred upon IRQ events + * indicating that the single-page DMA was completed. + */ alcor_data_set_dma(host); ctrl |= AU6601_DATA_DMA_MODE; host->dma_on = 1; alcor_write32(priv, data->sg_count * 0x1000, AU6601_REG_BLOCK_SIZE); } else { + /* + * For PIO transfers, we break down each operation + * into several sector-sized transfers. When one sector has + * complete, the IRQ handler will call this function again + * to kick off the transfer of the next sector. + */ alcor_write32(priv, data->blksz, AU6601_REG_BLOCK_SIZE); } @@ -776,8 +793,12 @@ static void alcor_pre_req(struct mmc_host *mmc, return; /* * We don't do DMA on "complex" transfers, i.e. with - * non-word-aligned buffers or lengths. Also, we don't bother - * with all the DMA setup overhead for short transfers. + * non-word-aligned buffers or lengths. A future improvement + * could be made to use temporary DMA bounce-buffers when these + * requirements are not met. + * + * Also, we don't bother with all the DMA setup overhead for + * short transfers. */ if (data->blocks * data->blksz < AU6601_MAX_DMA_BLOCK_SIZE) return; @@ -788,6 +809,8 @@ static void alcor_pre_req(struct mmc_host *mmc, for_each_sg(data->sg, sg, data->sg_len, i) { if (sg->length != AU6601_MAX_DMA_BLOCK_SIZE) return; + if (sg->offset != 0) + return; } /* This data might be unmapped at this time */ @@ -1038,26 +1061,21 @@ static void alcor_init_mmc(struct alcor_sdmmc_host *host) mmc->ops = &alcor_sdc_ops; /* The hardware does DMA data transfer of 4096 bytes to/from a single - * buffer address. Scatterlists are not supported, but upon DMA - * completion (signalled via IRQ), the original vendor driver does - * then immediately set up another DMA transfer of the next 4096 - * bytes. - * - * This means that we need to handle the I/O in 4096 byte chunks. - * Lacking a way to limit the sglist entries to 4096 bytes, we instead - * impose that only one segment is provided, with maximum size 4096, - * which also happens to be the minimum size. This means that the - * single-entry sglist handled by this driver can be handed directly - * to the hardware, nice and simple. + * buffer address. Scatterlists are not supported at the hardware + * level, however we can work with them at the driver level, + * provided that each segment is exactly 4096 bytes in size. + * Upon DMA completion of a single segment (signalled via IRQ), we + * immediately proceed to transfer the next segment from the + * scatterlist. * - * Unfortunately though, that means we only do 4096 bytes I/O per - * MMC command. A future improvement would be to make the driver - * accept sg lists and entries of any size, and simply iterate - * through them 4096 bytes at a time. + * The overall request is limited to 240 sectors, matching the + * original vendor driver. */ mmc->max_segs = AU6601_MAX_DMA_SEGMENTS; mmc->max_seg_size = AU6601_MAX_DMA_BLOCK_SIZE; - mmc->max_req_size = mmc->max_seg_size; + mmc->max_blk_count = 240; + mmc->max_req_size = mmc->max_blk_count * mmc->max_blk_size; + dma_set_max_seg_size(host->dev, mmc->max_seg_size); } static int alcor_pci_sdmmc_drv_probe(struct platform_device *pdev) diff --git a/include/linux/alcor_pci.h b/include/linux/alcor_pci.h index da973e8a2da8..4416df597526 100644 --- a/include/linux/alcor_pci.h +++ b/include/linux/alcor_pci.h @@ -23,7 +23,7 @@ #define AU6601_BASE_CLOCK 31000000 #define AU6601_MIN_CLOCK 150000 #define AU6601_MAX_CLOCK 208000000 -#define AU6601_MAX_DMA_SEGMENTS 1 +#define AU6601_MAX_DMA_SEGMENTS 64 #define AU6601_MAX_PIO_SEGMENTS 1 #define AU6601_MAX_DMA_BLOCK_SIZE 0x1000 #define AU6601_MAX_PIO_BLOCK_SIZE 0x200 |