From 5f52c3552946eafa13f89c949449d16ce2b58b24 Mon Sep 17 00:00:00 2001 From: Guennadi Liakhovetski Date: Mon, 7 Mar 2011 11:33:11 +0100 Subject: [PATCH] mmc: tmio: use PIO for short transfers This patch allows transferring of some requests in PIO and some in DMA mode and defaults to using DMA only for transfers longer than 8 bytes. This is especially useful with SDIO, which can have lots of 2- and 4-byte transfers, creating unnecessary high overhead, when executed in DMA. Signed-off-by: Guennadi Liakhovetski Acked-by: Paul Mundt Signed-off-by: Chris Ball --- drivers/mmc/host/tmio_mmc.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c index e88627b..32ab145 100644 --- a/drivers/mmc/host/tmio_mmc.c +++ b/drivers/mmc/host/tmio_mmc.c @@ -100,6 +100,8 @@ TMIO_STAT_CARD_REMOVE | TMIO_STAT_CARD_INSERT) #define TMIO_MASK_IRQ (TMIO_MASK_READOP | TMIO_MASK_WRITEOP | TMIO_MASK_CMD) +#define TMIO_MIN_DMA_LEN 8 + #define enable_mmc_irqs(host, i) \ do { \ u32 mask;\ @@ -147,6 +149,7 @@ struct tmio_mmc_host { struct platform_device *pdev; /* DMA support */ + bool force_pio; struct dma_chan *chan_rx; struct dma_chan *chan_tx; struct tasklet_struct dma_complete; @@ -385,6 +388,7 @@ static void tmio_mmc_reset_work(struct work_struct *work) host->cmd = NULL; host->data = NULL; host->mrq = NULL; + host->force_pio = false; spin_unlock_irqrestore(&host->lock, flags); @@ -404,6 +408,7 @@ tmio_mmc_finish_request(struct tmio_mmc_host *host) host->mrq = NULL; host->cmd = NULL; host->data = NULL; + host->force_pio = false; cancel_delayed_work(&host->delayed_reset_work); @@ -485,7 +490,7 @@ static void tmio_mmc_pio_irq(struct tmio_mmc_host *host) unsigned int count; unsigned long flags; - if (host->chan_tx || host->chan_rx) { + if ((host->chan_tx || host->chan_rx) && !host->force_pio) { pr_err("PIO IRQ in DMA mode!\n"); return; } else if (!data) { @@ -551,15 +556,11 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host) */ if (data->flags & MMC_DATA_READ) { - if (!host->chan_rx) - disable_mmc_irqs(host, TMIO_MASK_READOP); - else + if (host->chan_rx && !host->force_pio) tmio_check_bounce_buffer(host); dev_dbg(&host->pdev->dev, "Complete Rx request %p\n", host->mrq); } else { - if (!host->chan_tx) - disable_mmc_irqs(host, TMIO_MASK_WRITEOP); dev_dbg(&host->pdev->dev, "Complete Tx request %p\n", host->mrq); } @@ -583,7 +584,7 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host) if (!data) goto out; - if (host->chan_tx && (data->flags & MMC_DATA_WRITE)) { + if (host->chan_tx && (data->flags & MMC_DATA_WRITE) && !host->force_pio) { /* * Has all data been written out yet? Testing on SuperH showed, * that in most cases the first interrupt comes already with the @@ -596,11 +597,12 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host) disable_mmc_irqs(host, TMIO_STAT_DATAEND); tasklet_schedule(&host->dma_complete); } - } else if (host->chan_rx && (data->flags & MMC_DATA_READ)) { + } else if (host->chan_rx && (data->flags & MMC_DATA_READ) && !host->force_pio) { disable_mmc_irqs(host, TMIO_STAT_DATAEND); tasklet_schedule(&host->dma_complete); } else { tmio_mmc_do_data_irq(host); + disable_mmc_irqs(host, TMIO_MASK_READOP | TMIO_MASK_WRITEOP); } out: spin_unlock(&host->lock); @@ -649,12 +651,12 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host, */ if (host->data && !cmd->error) { if (host->data->flags & MMC_DATA_READ) { - if (!host->chan_rx) + if (host->force_pio || !host->chan_rx) enable_mmc_irqs(host, TMIO_MASK_READOP); else tasklet_schedule(&host->dma_issue); } else { - if (!host->chan_tx) + if (host->force_pio || !host->chan_tx) enable_mmc_irqs(host, TMIO_MASK_WRITEOP); else tasklet_schedule(&host->dma_issue); @@ -810,6 +812,11 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) goto pio; } + if (sg->length < TMIO_MIN_DMA_LEN) { + host->force_pio = true; + return; + } + disable_mmc_irqs(host, TMIO_STAT_RXRDY); /* The only sg element can be unaligned, use our bounce buffer then */ @@ -878,6 +885,11 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host) goto pio; } + if (sg->length < TMIO_MIN_DMA_LEN) { + host->force_pio = true; + return; + } + disable_mmc_irqs(host, TMIO_STAT_TXRQ); /* The only sg element can be unaligned, use our bounce buffer then */ @@ -1119,6 +1131,7 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) fail: host->mrq = NULL; + host->force_pio = false; mrq->cmd->error = ret; mmc_request_done(mmc, mrq); } -- 2.7.4