diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0396-dmaengine-bcm2835-limit-max-length-based-on-channel-.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0396-dmaengine-bcm2835-limit-max-length-based-on-channel-.patch | 114 |
1 files changed, 0 insertions, 114 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0396-dmaengine-bcm2835-limit-max-length-based-on-channel-.patch b/target/linux/brcm2708/patches-4.4/0396-dmaengine-bcm2835-limit-max-length-based-on-channel-.patch deleted file mode 100644 index 20fb886903..0000000000 --- a/target/linux/brcm2708/patches-4.4/0396-dmaengine-bcm2835-limit-max-length-based-on-channel-.patch +++ /dev/null @@ -1,114 +0,0 @@ -From 426f54e1e932f40b666b238ef37d0610fd35d0d0 Mon Sep 17 00:00:00 2001 -From: Martin Sperl <kernel@martin.sperl.org> -Date: Wed, 16 Mar 2016 12:25:00 -0700 -Subject: [PATCH] dmaengine: bcm2835: limit max length based on channel type - -The bcm2835 dma system has 2 basic types of dma-channels: -* "normal" channels -* "light" channels - -Lite channels are limited in several aspects: -* internal data-structure is 128 bit (not 256) -* does not support BCM2835_DMA_TDMODE (2D) -* DMA length register is limited to 16 bit. - so 0-65535 (not 0-65536 as mentioned in the official datasheet) -* BCM2835_DMA_S/D_IGNORE are not supported - -The detection of the type of mode is implemented by looking at -the LITE bit in the DEBUG register for each channel. -This allows automatic detection. - -Based on this the maximum block size is set to (64K - 4) or to 1G -and this limit is honored during generation of control block -chains. The effect is that when a LITE channel is used more -control blocks are used to do the same transfer (compared -to a normal channel). - -As there are several sources/target DREQS that are 32 bit wide -we need to have the transfer to be a multiple of 4 as this would -break the transfer otherwise. - -This is why the limit of (64K - 4) was chosen over the -alternative of (64K - 4K). - -Signed-off-by: Martin Sperl <kernel@martin.sperl.org> -Reviewed-by: Eric Anholt <eric@anholt.net> -Signed-off-by: Eric Anholt <eric@anholt.net> -Signed-off-by: Vinod Koul <vinod.koul@intel.com> ---- - drivers/dma/bcm2835-dma.c | 29 ++++++++++++++++++++++++++--- - 1 file changed, 26 insertions(+), 3 deletions(-) - ---- a/drivers/dma/bcm2835-dma.c -+++ b/drivers/dma/bcm2835-dma.c -@@ -81,6 +81,8 @@ struct bcm2835_chan { - - void __iomem *chan_base; - int irq_number; -+ -+ bool is_lite_channel; - }; - - struct bcm2835_desc { -@@ -169,6 +171,16 @@ struct bcm2835_desc { - #define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */ - #define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n)) - -+/* the max dma length for different channels */ -+#define MAX_DMA_LEN SZ_1G -+#define MAX_LITE_DMA_LEN (SZ_64K - 4) -+ -+static inline size_t bcm2835_dma_max_frame_length(struct bcm2835_chan *c) -+{ -+ /* lite and normal channels have different max frame length */ -+ return c->is_lite_channel ? MAX_LITE_DMA_LEN : MAX_DMA_LEN; -+} -+ - /* how many frames of max_len size do we need to transfer len bytes */ - static inline size_t bcm2835_dma_frames_for_length(size_t len, - size_t max_len) -@@ -217,8 +229,10 @@ static void bcm2835_dma_create_cb_set_le - size_t *total_len, - u32 finalextrainfo) - { -- /* set the length */ -- control_block->length = len; -+ size_t max_len = bcm2835_dma_max_frame_length(chan); -+ -+ /* set the length taking lite-channel limitations into account */ -+ control_block->length = min_t(u32, len, max_len); - - /* finished if we have no period_length */ - if (!period_len) -@@ -544,6 +558,7 @@ static struct dma_async_tx_descriptor *b - dma_addr_t src, dst; - u32 info = BCM2835_DMA_WAIT_RESP; - u32 extra = BCM2835_DMA_INT_EN; -+ size_t max_len = bcm2835_dma_max_frame_length(c); - size_t frames; - - /* Grab configuration */ -@@ -586,7 +601,10 @@ static struct dma_async_tx_descriptor *b - } - - /* calculate number of frames */ -- frames = DIV_ROUND_UP(buf_len, period_len); -+ frames = /* number of periods */ -+ DIV_ROUND_UP(buf_len, period_len) * -+ /* number of frames per period */ -+ bcm2835_dma_frames_for_length(period_len, max_len); - - /* - * allocate the CB chain -@@ -685,6 +703,11 @@ static int bcm2835_dma_chan_init(struct - c->ch = chan_id; - c->irq_number = irq; - -+ /* check in DEBUG register if this is a LITE channel */ -+ if (readl(c->chan_base + BCM2835_DMA_DEBUG) & -+ BCM2835_DMA_DEBUG_LITE) -+ c->is_lite_channel = true; -+ - return 0; - } - |