Re: [PATCH v2] i2c: designware: Get right data length
From: Andy Shevchenko
Date: Thu Feb 25 2021 - 10:07:33 EST
On Thu, Feb 25, 2021 at 10:26:31PM +0800, Liguang Zhang wrote:
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IC_DATA_CMD[11] indicates the first data byte received after the address
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phase for receive transfer in Master receiver or Slave receiver mode,
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this bit was set in some transfer flow. IC_DATA_CMD[7:0] contains the
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data to be transmitted or received on the I2C bus, so we should use the
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lower 8 bits to get the real data length.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
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Signed-off-by: Liguang Zhang <zhangliguang@xxxxxxxxxxxxxxxxx>
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---
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drivers/i2c/busses/i2c-designware-core.h | 2 ++
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drivers/i2c/busses/i2c-designware-master.c | 2 +-
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2 files changed, 3 insertions(+), 1 deletion(-)
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diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
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index 85307cfa7109..5392b82f68a4 100644
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--- a/drivers/i2c/busses/i2c-designware-core.h
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+++ b/drivers/i2c/busses/i2c-designware-core.h
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@@ -38,6 +38,8 @@
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#define DW_IC_CON_TX_EMPTY_CTRL BIT(8)
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#define DW_IC_CON_RX_FIFO_FULL_HLD_CTRL BIT(9)
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+#define DW_IC_DATA_CMD_DAT GENMASK(7, 0)
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+
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/*
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* Registers offset
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*/
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diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
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index d6425ad6e6a3..dd27b9dbe931 100644
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--- a/drivers/i2c/busses/i2c-designware-master.c
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+++ b/drivers/i2c/busses/i2c-designware-master.c
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@@ -432,7 +432,7 @@ i2c_dw_read(struct dw_i2c_dev *dev)
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regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
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/* Ensure length byte is a valid value */
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if (flags & I2C_M_RECV_LEN &&
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- tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
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+ (tmp & DW_IC_DATA_CMD_DAT) <= I2C_SMBUS_BLOCK_MAX && tmp > 0) {
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len = i2c_dw_recv_len(dev, tmp);
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}
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*buf++ = tmp;
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--
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2.19.1.6.gb485710b
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--
With Best Regards,
Andy Shevchenko