diff options
| author | Max Filippov <jcmvbkbc@gmail.com> | 2013-12-25 16:01:30 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-08 04:15:39 +0400 |
| commit | 8f668fbbd571bbd5187a9a0eae150b768fc388ac (patch) | |
| tree | 3def8b18a00f20ce2ea41acd3f831450ac982ac7 | |
| parent | 543d7784b07ffd16cc82a9cb4e1e0323fd0040f1 (diff) | |
| download | linux-8f668fbbd571bbd5187a9a0eae150b768fc388ac.tar.xz | |
USB: c67x00: add proper delays to HPI read/write
According to CY7C67300 specification HPI read and write cycle duration
Tcyc must be at least 6T long, where T is 1/48MHz, which is 125ns.
Without this delay fast host processor cannot write to chip registers.
Add proper ndelay to hpi_{read,write}_reg.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/c67x00/c67x00-ll-hpi.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/usb/c67x00/c67x00-ll-hpi.c b/drivers/usb/c67x00/c67x00-ll-hpi.c index 3a1ca4dfc83a..cd2c6ed67493 100644 --- a/drivers/usb/c67x00/c67x00-ll-hpi.c +++ b/drivers/usb/c67x00/c67x00-ll-hpi.c @@ -22,6 +22,7 @@ */ #include <asm/byteorder.h> +#include <linux/delay.h> #include <linux/io.h> #include <linux/jiffies.h> #include <linux/usb/c67x00.h> @@ -73,13 +74,22 @@ struct c67x00_lcp_int_data { #define HPI_ADDR 2 #define HPI_STATUS 3 +/* + * According to CY7C67300 specification (tables 140 and 141) HPI read and + * write cycle duration Tcyc must be at least 6T long, where T is 1/48MHz, + * which is 125ns. + */ +#define HPI_T_CYC_NS 125 + static inline u16 hpi_read_reg(struct c67x00_device *dev, int reg) { + ndelay(HPI_T_CYC_NS); return __raw_readw(dev->hpi.base + reg * dev->hpi.regstep); } static inline void hpi_write_reg(struct c67x00_device *dev, int reg, u16 value) { + ndelay(HPI_T_CYC_NS); __raw_writew(value, dev->hpi.base + reg * dev->hpi.regstep); } |