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011f2c26f1
As usual these patches were extracted and rebased from the raspberry pi repo: https://github.com/raspberrypi/linux/tree/rpi-4.4.y Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
171 lines
5.4 KiB
Diff
171 lines
5.4 KiB
Diff
From f505fc71c85f0f87e45d4890ae9e7762c38e6c9a Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Tue, 8 Mar 2016 09:49:16 +0000
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Subject: [PATCH] bcm2835-mmc: Only claim one DMA channel
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With both MMC controllers enabled there are few DMA channels left. The
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bcm2835-mmc driver only uses DMA in one direction at a time, so it
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doesn't need to claim two channels.
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See: https://github.com/raspberrypi/linux/issues/1327
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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arch/arm/boot/dts/bcm2708_common.dtsi | 5 +--
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drivers/mmc/host/bcm2835-mmc.c | 69 +++++++++++++++++++++++++----------
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2 files changed, 51 insertions(+), 23 deletions(-)
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--- a/arch/arm/boot/dts/bcm2708_common.dtsi
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+++ b/arch/arm/boot/dts/bcm2708_common.dtsi
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@@ -232,9 +232,8 @@
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reg = <0x7e300000 0x100>;
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interrupts = <2 30>;
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clocks = <&clk_mmc>;
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- dmas = <&dma 11>,
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- <&dma 11>;
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- dma-names = "tx", "rx";
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+ dmas = <&dma 11>;
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+ dma-names = "rx-tx";
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brcm,overclock-50 = <0>;
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status = "disabled";
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};
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--- a/drivers/mmc/host/bcm2835-mmc.c
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+++ b/drivers/mmc/host/bcm2835-mmc.c
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@@ -108,8 +108,9 @@ struct bcm2835_host {
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u32 shadow;
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/*DMA part*/
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- struct dma_chan *dma_chan_rx; /* DMA channel for reads */
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- struct dma_chan *dma_chan_tx; /* DMA channel for writes */
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+ struct dma_chan *dma_chan_rxtx; /* DMA channel for reads and writes */
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+ struct dma_slave_config dma_cfg_rx;
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+ struct dma_slave_config dma_cfg_tx;
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struct dma_async_tx_descriptor *tx_desc; /* descriptor */
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bool have_dma;
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@@ -342,7 +343,7 @@ static void bcm2835_mmc_dma_complete(voi
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if (host->data && !(host->data->flags & MMC_DATA_WRITE)) {
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/* otherwise handled in SDHCI IRQ */
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- dma_chan = host->dma_chan_rx;
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+ dma_chan = host->dma_chan_rxtx;
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dir_data = DMA_FROM_DEVICE;
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dma_unmap_sg(dma_chan->device->dev,
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@@ -493,16 +494,21 @@ static void bcm2835_mmc_transfer_dma(str
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if (host->blocks == 0)
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return;
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+ dma_chan = host->dma_chan_rxtx;
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if (host->data->flags & MMC_DATA_READ) {
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- dma_chan = host->dma_chan_rx;
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dir_data = DMA_FROM_DEVICE;
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dir_slave = DMA_DEV_TO_MEM;
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} else {
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- dma_chan = host->dma_chan_tx;
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dir_data = DMA_TO_DEVICE;
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dir_slave = DMA_MEM_TO_DEV;
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}
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+ /* The parameters have already been validated, so this will not fail */
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+ (void)dmaengine_slave_config(dma_chan,
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+ (dir_data == DMA_FROM_DEVICE) ?
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+ &host->dma_cfg_rx :
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+ &host->dma_cfg_tx);
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+
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BUG_ON(!dma_chan->device);
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BUG_ON(!dma_chan->device->dev);
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BUG_ON(!host->data->sg);
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@@ -936,7 +942,7 @@ static void bcm2835_mmc_data_irq(struct
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if (host->data->flags & MMC_DATA_WRITE) {
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/* IRQ handled here */
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- dma_chan = host->dma_chan_tx;
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+ dma_chan = host->dma_chan_rxtx;
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dir_data = DMA_TO_DEVICE;
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dma_unmap_sg(dma_chan->device->dev,
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host->data->sg, host->data->sg_len,
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@@ -1316,28 +1322,47 @@ static int bcm2835_mmc_add_host(struct b
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dev_info(dev, "Forcing PIO mode\n");
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host->have_dma = false;
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#else
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- if (IS_ERR_OR_NULL(host->dma_chan_tx) ||
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- IS_ERR_OR_NULL(host->dma_chan_rx)) {
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- dev_err(dev, "%s: Unable to initialise DMA channels. Falling back to PIO\n",
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+ if (IS_ERR_OR_NULL(host->dma_chan_rxtx)) {
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+ dev_err(dev, "%s: Unable to initialise DMA channel. Falling back to PIO\n",
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DRIVER_NAME);
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host->have_dma = false;
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} else {
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- dev_info(dev, "DMA channels allocated");
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- host->have_dma = true;
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+ dev_info(dev, "DMA channel allocated");
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cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
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cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
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cfg.slave_id = 11; /* DREQ channel */
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+ /* Validate the slave configurations */
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+
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cfg.direction = DMA_MEM_TO_DEV;
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cfg.src_addr = 0;
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cfg.dst_addr = host->bus_addr + SDHCI_BUFFER;
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- ret = dmaengine_slave_config(host->dma_chan_tx, &cfg);
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- cfg.direction = DMA_DEV_TO_MEM;
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- cfg.src_addr = host->bus_addr + SDHCI_BUFFER;
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- cfg.dst_addr = 0;
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- ret = dmaengine_slave_config(host->dma_chan_rx, &cfg);
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+ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
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+
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+ if (ret == 0) {
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+ host->dma_cfg_tx = cfg;
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+
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+ cfg.direction = DMA_DEV_TO_MEM;
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+ cfg.src_addr = host->bus_addr + SDHCI_BUFFER;
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+ cfg.dst_addr = 0;
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+
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+ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
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+ }
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+
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+ if (ret == 0) {
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+ host->dma_cfg_rx = cfg;
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+
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+ host->use_dma = true;
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+ } else {
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+ pr_err("%s: unable to configure DMA channel. "
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+ "Faling back to PIO\n",
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+ mmc_hostname(mmc));
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+ dma_release_channel(host->dma_chan_rxtx);
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+ host->dma_chan_rxtx = NULL;
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+ host->use_dma = false;
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+ }
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}
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#endif
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mmc->max_segs = 128;
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@@ -1416,16 +1441,20 @@ static int bcm2835_mmc_probe(struct plat
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#ifndef FORCE_PIO
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if (node) {
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- host->dma_chan_tx = dma_request_slave_channel(dev, "tx");
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- host->dma_chan_rx = dma_request_slave_channel(dev, "rx");
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+ host->dma_chan_rxtx = dma_request_slave_channel(dev, "rx-tx");
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+ if (!host->dma_chan_rxtx)
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+ host->dma_chan_rxtx =
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+ dma_request_slave_channel(dev, "tx");
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+ if (!host->dma_chan_rxtx)
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+ host->dma_chan_rxtx =
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+ dma_request_slave_channel(dev, "rx");
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} else {
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dma_cap_mask_t mask;
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dma_cap_zero(mask);
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/* we don't care about the channel, any would work */
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dma_cap_set(DMA_SLAVE, mask);
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- host->dma_chan_tx = dma_request_channel(mask, NULL, NULL);
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- host->dma_chan_rx = dma_request_channel(mask, NULL, NULL);
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+ host->dma_chan_rxtx = dma_request_channel(mask, NULL, NULL);
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}
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#endif
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clk = devm_clk_get(dev, NULL);
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