From 2ddc982a6c172c141183ac954d44f01bc4f2fe72 Mon Sep 17 00:00:00 2001 From: Alexandru Tachici Date: Fri, 21 Feb 2020 14:06:55 +0200 Subject: iio: industrialio-core: Fix debugfs read Currently iio_debugfs_read_reg calls debugfs_reg_access every time it is ran. Reading the same hardware register multiple times during the same reading of a debugfs file can cause unintended effects. For example for each: cat iio:device0/direct_reg_access the file_operations.read function will be called at least twice. First will return the full length of the string in bytes and the second will return 0. This patch makes iio_debugfs_read_reg to call debugfs_reg_access only when the user's buffer position (*ppos) is 0. (meaning it is the beginning of a new reading of the debugfs file). Fixes: e553f182d55b ("staging: iio: core: Introduce debugfs support, add support for direct register access") Signed-off-by: Alexandru Ardelean Signed-off-by: Alexandru Tachici Signed-off-by: Jonathan Cameron --- include/linux/iio/iio.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h index 862ce0019eba..eed58ed2f368 100644 --- a/include/linux/iio/iio.h +++ b/include/linux/iio/iio.h @@ -568,6 +568,8 @@ struct iio_dev { #if defined(CONFIG_DEBUG_FS) struct dentry *debugfs_dentry; unsigned cached_reg_addr; + char read_buf[20]; + unsigned int read_buf_len; #endif }; -- cgit v1.2.3