diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0175-bcm2835-sdhost-Only-claim-one-DMA-channel.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0175-bcm2835-sdhost-Only-claim-one-DMA-channel.patch | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0175-bcm2835-sdhost-Only-claim-one-DMA-channel.patch b/target/linux/brcm2708/patches-4.4/0175-bcm2835-sdhost-Only-claim-one-DMA-channel.patch new file mode 100644 index 0000000000..fb68bcb5f8 --- /dev/null +++ b/target/linux/brcm2708/patches-4.4/0175-bcm2835-sdhost-Only-claim-one-DMA-channel.patch @@ -0,0 +1,160 @@ +From 06c169985c0884ce67377c79d27383e23f41e2cd Mon Sep 17 00:00:00 2001 +From: Phil Elwell <phil@raspberrypi.org> +Date: Mon, 7 Mar 2016 16:46:39 +0000 +Subject: [PATCH 175/180] bcm2835-sdhost: Only claim one DMA channel + +With both MMC controllers enabled there are few DMA channels left. The +bcm2835-sdhost driver only uses DMA in one direction at a time, so it +doesn't need to claim two channels. + +See: https://github.com/raspberrypi/linux/issues/1327 + +Signed-off-by: Phil Elwell <phil@raspberrypi.org> +--- + arch/arm/boot/dts/bcm2708_common.dtsi | 5 +-- + drivers/mmc/host/bcm2835-sdhost.c | 70 ++++++++++++++++++++++++----------- + 2 files changed, 50 insertions(+), 25 deletions(-) + +--- a/arch/arm/boot/dts/bcm2708_common.dtsi ++++ b/arch/arm/boot/dts/bcm2708_common.dtsi +@@ -136,9 +136,8 @@ + reg = <0x7e202000 0x100>; + interrupts = <2 24>; + clocks = <&clk_core>; +- dmas = <&dma 13>, +- <&dma 13>; +- dma-names = "tx", "rx"; ++ dmas = <&dma 13>; ++ dma-names = "rx-tx"; + brcm,overclock-50 = <0>; + brcm,pio-limit = <1>; + status = "disabled"; +--- a/drivers/mmc/host/bcm2835-sdhost.c ++++ b/drivers/mmc/host/bcm2835-sdhost.c +@@ -185,9 +185,10 @@ struct bcm2835_host { + unsigned int debug:1; /* Enable debug output */ + + /*DMA part*/ +- struct dma_chan *dma_chan_rx; /* DMA channel for reads */ +- struct dma_chan *dma_chan_tx; /* DMA channel for writes */ +- struct dma_chan *dma_chan; /* Channel in used */ ++ struct dma_chan *dma_chan_rxtx; /* DMA channel for reads and writes */ ++ struct dma_chan *dma_chan; /* Channel in use */ ++ struct dma_slave_config dma_cfg_rx; ++ struct dma_slave_config dma_cfg_tx; + struct dma_async_tx_descriptor *dma_desc; + u32 dma_dir; + u32 drain_words; +@@ -771,12 +772,11 @@ static void bcm2835_sdhost_prepare_dma(s + log_event("PRD<", (u32)data, 0); + pr_debug("bcm2835_sdhost_prepare_dma()\n"); + ++ dma_chan = host->dma_chan_rxtx; + if (data->flags & MMC_DATA_READ) { +- dma_chan = host->dma_chan_rx; + dir_data = DMA_FROM_DEVICE; + dir_slave = DMA_DEV_TO_MEM; + } else { +- dma_chan = host->dma_chan_tx; + dir_data = DMA_TO_DEVICE; + dir_slave = DMA_MEM_TO_DEV; + } +@@ -813,6 +813,12 @@ static void bcm2835_sdhost_prepare_dma(s + host->drain_words = len/4; + } + ++ /* The parameters have already been validated, so this will not fail */ ++ (void)dmaengine_slave_config(dma_chan, ++ (dir_data == DMA_FROM_DEVICE) ? ++ &host->dma_cfg_rx : ++ &host->dma_cfg_tx); ++ + len = dma_map_sg(dma_chan->device->dev, data->sg, data->sg_len, + dir_data); + +@@ -1805,28 +1811,46 @@ int bcm2835_sdhost_add_host(struct bcm28 + spin_lock_init(&host->lock); + + if (host->allow_dma) { +- if (IS_ERR_OR_NULL(host->dma_chan_tx) || +- IS_ERR_OR_NULL(host->dma_chan_rx)) { +- pr_err("%s: unable to initialise DMA channels. " ++ if (IS_ERR_OR_NULL(host->dma_chan_rxtx)) { ++ pr_err("%s: unable to initialise DMA channel. " + "Falling back to PIO\n", + mmc_hostname(mmc)); + host->use_dma = false; + } else { +- host->use_dma = true; +- + cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; + cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES; + cfg.slave_id = 13; /* DREQ channel */ + ++ /* Validate the slave configurations */ ++ + cfg.direction = DMA_MEM_TO_DEV; + cfg.src_addr = 0; + cfg.dst_addr = host->bus_addr + SDDATA; +- ret = dmaengine_slave_config(host->dma_chan_tx, &cfg); + +- cfg.direction = DMA_DEV_TO_MEM; +- cfg.src_addr = host->bus_addr + SDDATA; +- cfg.dst_addr = 0; +- ret = dmaengine_slave_config(host->dma_chan_rx, &cfg); ++ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg); ++ ++ if (ret == 0) { ++ host->dma_cfg_tx = cfg; ++ ++ cfg.direction = DMA_DEV_TO_MEM; ++ cfg.src_addr = host->bus_addr + SDDATA; ++ cfg.dst_addr = 0; ++ ++ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg); ++ } ++ ++ if (ret == 0) { ++ host->dma_cfg_rx = cfg; ++ ++ host->use_dma = true; ++ } else { ++ pr_err("%s: unable to configure DMA channel. " ++ "Falling back to PIO\n", ++ mmc_hostname(mmc)); ++ dma_release_channel(host->dma_chan_rxtx); ++ host->dma_chan_rxtx = NULL; ++ host->use_dma = false; ++ } + } + } else { + host->use_dma = false; +@@ -1948,19 +1972,21 @@ static int bcm2835_sdhost_probe(struct p + + if (host->allow_dma) { + if (node) { +- host->dma_chan_tx = +- dma_request_slave_channel(dev, "tx"); +- host->dma_chan_rx = +- dma_request_slave_channel(dev, "rx"); ++ host->dma_chan_rxtx = ++ dma_request_slave_channel(dev, "rx-tx"); ++ if (!host->dma_chan_rxtx) ++ host->dma_chan_rxtx = ++ dma_request_slave_channel(dev, "tx"); ++ if (!host->dma_chan_rxtx) ++ host->dma_chan_rxtx = ++ dma_request_slave_channel(dev, "rx"); + } else { + dma_cap_mask_t mask; + + dma_cap_zero(mask); + /* we don't care about the channel, any would work */ + dma_cap_set(DMA_SLAVE, mask); +- host->dma_chan_tx = +- dma_request_channel(mask, NULL, NULL); +- host->dma_chan_rx = ++ host->dma_chan_rxtx = + dma_request_channel(mask, NULL, NULL); + } + } |