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Commit 8f668fbb authored by Max Filippov's avatar Max Filippov Committed by Greg Kroah-Hartman
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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: default avatarMax Filippov <jcmvbkbc@gmail.com>
Acked-by: default avatarPeter Korsgaard <peter@korsgaard.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 543d7784

drivers/usb/c67x00/c67x00-ll-hpi.c

+10 −0
Original line number Diff line number Diff line
@@ -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);

}