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i2c: rcar: wait for data empty before starting DMA 

When sending with DMA, the driver transfers the first byte with PIO (as
documented). However, it started DMA right after the first byte was
written. This worked, but was not according to the datasheet which
suggests to wait until data register was empty again. Implement this.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
hifive-unleashed-5.2
Wolfram Sang 2019-03-05 18:54:34 +01:00 committed by Wolfram Sang
parent 03f85e380f
commit 94e290b0e9
1 changed files with 4 additions and 7 deletions
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11
drivers/i2c/busses/i2c-rcar.c
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@ -480,6 +480,10 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
if (!(msr & MDE))
return;
/* Check if DMA can be enabled and take over */
if (priv->pos == 1 && rcar_i2c_dma(priv))
return;
if (priv->pos < msg->len) {
/*
* Prepare next data to ICRXTX register.
@ -490,13 +494,6 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
*/
rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
priv->pos++;
/*
* Try to use DMA to transmit the rest of the data if
* address transfer phase just finished.
*/
if (msr & MAT)
rcar_i2c_dma(priv);
} else {
/*
* The last data was pushed to ICRXTX on _PREV_ empty irq.