[i2c] [PATCH 1 of 2] Clean up of i2c-nforce2
Oleg Ryjkov
olegr at olegr.ca
Sun Oct 7 08:29:34 CEST 2007
Hi Jean, hi list,
> Hi Oleg,
>
> Sorry for the late answer.
>
> On Fri, 31 Aug 2007 00:15:16 -0700, Oleg Ryjkov wrote:
> > This is the first part of the patch that adds a function to reset the
> > nvidia MCP51/55 i2c controller, if something bad happens to it (i.e.
> > a slave sends a wrong byte count during a block transaction).
> >
> > This patch just adds nforce2_check_status function. It was originally
> > written by Hans-Frieder Vogt <hfvogt at gmx.net>, and was posted on this
> > list around October 2006 (see
> > http://lists.lm-sensors.org/pipermail/i2c/2006-October/000380.html).
> > However, unfortunately, he never got around to submitting it to the
> > kernel.
> > The reason that I'm the one sending it is is:
> > - I relied on it for the second part of the patch,
> > - It makes the driver code cleaner/better.
>
> I agree that it makes the code nicer. For HZ >= 250, it also makes most
> transactions faster. It makes the short transactions slower though
> (those that were fitting in the udelay(500)) for all values of HZ but
> that's probably not a big problem on practice.
>
Actually, from what I've seen most of the transactions were completed within
2000-3000 usecs anyways(on MCP51) so this change indeed generates some speedup.
> >
> > Signed-off-by: Oleg Ryjkov <olegr at google.com>
> >
> > --- linux-2.6-untouched/drivers/i2c/busses/i2c-nforce2.c 2007-08-13 18:28:26.000000000 -0700
> > +++ linux-2.6/drivers/i2c/busses/i2c-nforce2.c 2007-08-30 19:38:13.000000000 -0700
> > @@ -98,15 +98,39 @@
> > #define NVIDIA_SMB_PRTCL_BLOCK_DATA 0x0a
> > #define NVIDIA_SMB_PRTCL_PEC 0x80
> >
> > +/* Misc definitions */
> > +#define MAX_TIMEOUT 100
> > +
> > static struct pci_driver nforce2_driver;
> >
> > +static int nforce2_check_status(struct i2c_adapter * adap) {
>
> Coding style: opening curly brace goes at the beginning of the next
> line.
Changed.
>
> > + struct nforce2_smbus *smbus = adap->algo_data;
> > + int timeout = 0;
> > + unsigned char temp;
> > +
> > + do {
> > + msleep(1);
> > + temp = inb_p(NVIDIA_SMB_STS);
> > + } while ((!temp) && (timeout++ < MAX_TIMEOUT));
> > +
> > + if ((~temp & NVIDIA_SMB_STS_DONE) && (timeout >= MAX_TIMEOUT)) {
>
> (~temp & NVIDIA_SMB_STS_DONE) is better written
> !(temp & NVIDIA_SMB_STS_DONE).
Changed.
>
> I think that this test can be simplified. Checking for the DONE bit not
> being set should be enough. If that bit was set, then the while loop
> would have exited before the timeout. Or am I missing something?
>
I've changed that slightly - first we check whether timeout has been
exceeded, then make sure that DONE bit is one and the status is 0. I
find this more intuitive than before. This way the error messages better
reflect the actual error condition.
> > + dev_dbg(&adap->dev, "SMBus Timeout (0x%02x)!\n", temp);
> > + return -1;
> > + }
> > + if ((~temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
>
> Then this test can be simplified as well: no need to check again for
> the DONE bit not being set, as you checked this above already.
>
See the previous comment.
> > + dev_dbg(&adap->dev, "Transaction failed (0x%02x)!\n", temp);
> > + return -1;
> > + }
> > + return 0;
> > +}
> > +
> > /* Return -1 on error */
> > static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
> > unsigned short flags, char read_write,
> > u8 command, int size, union i2c_smbus_data * data)
> > {
> > struct nforce2_smbus *smbus = adap->algo_data;
> > - unsigned char protocol, pec, temp;
> > + unsigned char protocol, pec;
> > u8 len;
> > int i;
> >
> > @@ -170,22 +194,9 @@
> > outb_p((addr & 0x7f) << 1, NVIDIA_SMB_ADDR);
> > outb_p(protocol, NVIDIA_SMB_PRTCL);
> >
> > - temp = inb_p(NVIDIA_SMB_STS);
> > -
> > - if (~temp & NVIDIA_SMB_STS_DONE) {
> > - udelay(500);
> > - temp = inb_p(NVIDIA_SMB_STS);
> > - }
> > - if (~temp & NVIDIA_SMB_STS_DONE) {
> > - msleep(10);
> > - temp = inb_p(NVIDIA_SMB_STS);
> > - }
> > -
> > - if ((~temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
> > - dev_dbg(&adap->dev, "SMBus Timeout! (0x%02x)\n", temp);
> > + if (nforce2_check_status(adap))
> > return -1;
> > - }
> > -
> > +
>
> You patch is introducing trailing white space here, please clean up.
>
Changed.
> > if (read_write == I2C_SMBUS_WRITE)
> > return 0;
> >
> > @@ -202,7 +213,12 @@
> >
> > case I2C_SMBUS_BLOCK_DATA:
> > len = inb_p(NVIDIA_SMB_BCNT);
> > - len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);
> > + if ((len <= 0) || (len > I2C_SMBUS_BLOCK_MAX)) {
> > + dev_err(&adap->dev, "Transaction failed"
>
> Missing space at end of string.
Changed.
>
> > + "(requested block size: 0x%02x)"
> > + "\n", len);
>
> Please move the \n at the end of the previous line.
Changed.
>
> > + return -1;
> > + }
> > for (i = 0; i < len; i++)
> > data->block[i+1] = inb_p(NVIDIA_SMB_DATA + i);
> > data->block[0] = len;
>
>
> --
> Jean Delvare
Thank you for the careful review.
Oleg Ryjkov
Signed-off-by: Oleg Ryjkov <olegr at olegr.ca>
--- linux-2.6-untouched/drivers/i2c/busses/i2c-nforce2.c 2007-10-06 20:17:53.000000000 -0400
+++ linux-2.6/drivers/i2c/busses/i2c-nforce2.c 2007-10-07 00:10:14.000000000 -0400
@@ -98,15 +98,40 @@
#define NVIDIA_SMB_PRTCL_BLOCK_DATA 0x0a
#define NVIDIA_SMB_PRTCL_PEC 0x80
+/* Misc definitions */
+#define MAX_TIMEOUT 100
+
static struct pci_driver nforce2_driver;
+static int nforce2_check_status(struct i2c_adapter *adap)
+{
+ struct nforce2_smbus *smbus = adap->algo_data;
+ int timeout = 0;
+ unsigned char temp;
+
+ do {
+ msleep(1);
+ temp = inb_p(NVIDIA_SMB_STS);
+ } while ((!temp) && (timeout++ < MAX_TIMEOUT));
+
+ if (timeout >= MAX_TIMEOUT) {
+ dev_dbg(&adap->dev, "SMBus Timeout (0x%02x)!\n", temp);
+ return -1;
+ }
+ if (!(temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
+ dev_dbg(&adap->dev, "Transaction failed (0x%02x)!\n", temp);
+ return -1;
+ }
+ return 0;
+}
+
/* Return -1 on error */
static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
unsigned short flags, char read_write,
u8 command, int size, union i2c_smbus_data * data)
{
struct nforce2_smbus *smbus = adap->algo_data;
- unsigned char protocol, pec, temp;
+ unsigned char protocol, pec;
u8 len;
int i;
@@ -170,21 +195,8 @@
outb_p((addr & 0x7f) << 1, NVIDIA_SMB_ADDR);
outb_p(protocol, NVIDIA_SMB_PRTCL);
- temp = inb_p(NVIDIA_SMB_STS);
-
- if (~temp & NVIDIA_SMB_STS_DONE) {
- udelay(500);
- temp = inb_p(NVIDIA_SMB_STS);
- }
- if (~temp & NVIDIA_SMB_STS_DONE) {
- msleep(10);
- temp = inb_p(NVIDIA_SMB_STS);
- }
-
- if ((~temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
- dev_dbg(&adap->dev, "SMBus Timeout! (0x%02x)\n", temp);
+ if (nforce2_check_status(adap))
return -1;
- }
if (read_write == I2C_SMBUS_WRITE)
return 0;
@@ -202,7 +214,12 @@
case I2C_SMBUS_BLOCK_DATA:
len = inb_p(NVIDIA_SMB_BCNT);
- len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);
+ if ((len <= 0) || (len > I2C_SMBUS_BLOCK_MAX)) {
+ dev_err(&adap->dev, "Transaction failed "
+ "(received block size: 0x%02x)\n",
+ len);
+ return -1;
+ }
for (i = 0; i < len; i++)
data->block[i+1] = inb_p(NVIDIA_SMB_DATA + i);
data->block[0] = len;
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