diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0024-bcm2835-dma-Limit-cyclic-transfers-on-lite-channels-.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0024-bcm2835-dma-Limit-cyclic-transfers-on-lite-channels-.patch | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0024-bcm2835-dma-Limit-cyclic-transfers-on-lite-channels-.patch b/target/linux/brcm2708/patches-4.4/0024-bcm2835-dma-Limit-cyclic-transfers-on-lite-channels-.patch new file mode 100644 index 0000000000..4461fec7a9 --- /dev/null +++ b/target/linux/brcm2708/patches-4.4/0024-bcm2835-dma-Limit-cyclic-transfers-on-lite-channels-.patch @@ -0,0 +1,37 @@ +From c7e464c38d38ad59899c94dfad6c3455c18f7d76 Mon Sep 17 00:00:00 2001 +From: Matthias Reichl <hias@horus.com> +Date: Sun, 11 Oct 2015 12:28:30 +0200 +Subject: [PATCH 024/127] bcm2835-dma: Limit cyclic transfers on lite channels + to 32k + +Transfers larger than 32k cause repeated clicking with I2S soundcards. +The exact reason is yet unknown, so limit to 32k as bcm2708-dmaengine +did as an intermediate fix. +--- + drivers/dma/bcm2835-dma.c | 8 +++++++- + 1 file changed, 7 insertions(+), 1 deletion(-) + +--- a/drivers/dma/bcm2835-dma.c ++++ b/drivers/dma/bcm2835-dma.c +@@ -144,6 +144,12 @@ struct bcm2835_desc { + */ + #define MAX_LITE_TRANSFER (SZ_64K - 4) + ++/* ++ * Transfers larger than 32k cause issues with the bcm2708-i2s driver, ++ * so limit transfer size to 32k as bcm2708-dmaengine did. ++ */ ++#define MAX_CYCLIC_LITE_TRANSFER SZ_32K ++ + static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d) + { + return container_of(d, struct bcm2835_dmadev, ddev); +@@ -412,7 +418,7 @@ static struct dma_async_tx_descriptor *b + d->c = c; + d->dir = direction; + if (c->ch >= 8) /* LITE channel */ +- max_size = MAX_LITE_TRANSFER; ++ max_size = MAX_CYCLIC_LITE_TRANSFER; + else + max_size = MAX_NORMAL_TRANSFER; + period_len = min(period_len, max_size); |