Re: [PATCH v2 3/4] i2c: designware: Allow SMBus block reads up to 255 bytes in length
From: Wolfram Sang <wsa@kernel.org>
Date: 2020-09-17 20:57:09
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On Wed, Sep 16, 2020 at 10:22:55PM -0700, Sultan Alsawaf wrote:
From: Sultan Alsawaf <redacted> According to the SMBus 3.0 protocol specification, block transfer limits were increased from 32 bytes to 255 bytes. Remove the obsolete 32-byte limitation.
Sadly, it is not that easy. We are trying to extend BLOCK_MAX to 255 (SMBus 3 specs) but there are various things to be considered, especially with buffers and when passing it to userspace. Check here for the discussion (and you are welcome to join, of course): http://patchwork.ozlabs.org/project/linux-i2c/list/?submitter=79741&state=*
quoted hunk ↗ jump to hunk
Signed-off-by: Sultan Alsawaf <redacted> --- drivers/i2c/busses/i2c-designware-master.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index 22f28516bca7..5bd64bd17d94 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c@@ -433,7 +433,7 @@ i2c_dw_read(struct dw_i2c_dev *dev) regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); if (flags & I2C_M_RECV_LEN) { /* Ensure length byte is a valid value */ - if (tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) + if (tmp > 0) len = i2c_dw_recv_len(dev, tmp); else len = i2c_dw_recv_len(dev, len);-- 2.28.0
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