[net,v2,1/2] net: sfp: initialize sfp->i2c_block_size at sfp allocation
Commit Message
sfp->i2c_block_size is initialized at SFP module insertion in
sfp_sm_mod_probe(). Because of that, if SFP module was never inserted
since boot, sfp_read() call will lead to zero-length I2C read attempt,
and not all I2C controllers are happy with zero-length reads.
One way to issue sfp_read() on empty SFP cage is to execute ethtool -m.
If SFP module was never plugged since boot, there will be a zero-length
I2C read attempt.
# ethtool -m xge0
i2c i2c-3: adapter quirk: no zero length (addr 0x0050, size 0, read)
Cannot get Module EEPROM data: Operation not supported
If SFP module was plugged then removed at least once,
sfp->i2c_block_size will be initialized and ethtool -m will fail with
different exit code and without I2C error
# ethtool -m xge0
Cannot get Module EEPROM data: Remote I/O error
Fix this by initializing sfp->i2_block_size at struct sfp allocation
stage so no wild sfp_read() could issue zero-length I2C read.
Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Fixes: 0d035bed2a4a ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround")
Cc: stable@vger.kernel.org
---
drivers/net/phy/sfp.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
Comments
On Thu, Apr 06, 2023 at 04:08:32PM +0300, Ivan Bornyakov wrote:
> sfp->i2c_block_size is initialized at SFP module insertion in
> sfp_sm_mod_probe(). Because of that, if SFP module was never inserted
> since boot, sfp_read() call will lead to zero-length I2C read attempt,
> and not all I2C controllers are happy with zero-length reads.
>
> One way to issue sfp_read() on empty SFP cage is to execute ethtool -m.
> If SFP module was never plugged since boot, there will be a zero-length
> I2C read attempt.
>
> # ethtool -m xge0
> i2c i2c-3: adapter quirk: no zero length (addr 0x0050, size 0, read)
> Cannot get Module EEPROM data: Operation not supported
>
> If SFP module was plugged then removed at least once,
> sfp->i2c_block_size will be initialized and ethtool -m will fail with
> different exit code and without I2C error
>
> # ethtool -m xge0
> Cannot get Module EEPROM data: Remote I/O error
>
> Fix this by initializing sfp->i2_block_size at struct sfp allocation
> stage so no wild sfp_read() could issue zero-length I2C read.
>
> Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
> Fixes: 0d035bed2a4a ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround")
> Cc: stable@vger.kernel.org
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
@@ -212,6 +212,12 @@ static const enum gpiod_flags gpio_flags[] = {
#define SFP_PHY_ADDR 22
#define SFP_PHY_ADDR_ROLLBALL 17
+/* SFP_EEPROM_BLOCK_SIZE is the size of data chunk to read the EEPROM
+ * at a time. Some SFP modules and also some Linux I2C drivers do not like
+ * reads longer than 16 bytes.
+ */
+#define SFP_EEPROM_BLOCK_SIZE 16
+
struct sff_data {
unsigned int gpios;
bool (*module_supported)(const struct sfp_eeprom_id *id);
@@ -1928,11 +1934,7 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
u8 check;
int ret;
- /* Some SFP modules and also some Linux I2C drivers do not like reads
- * longer than 16 bytes, so read the EEPROM in chunks of 16 bytes at
- * a time.
- */
- sfp->i2c_block_size = 16;
+ sfp->i2c_block_size = SFP_EEPROM_BLOCK_SIZE;
ret = sfp_read(sfp, false, 0, &id.base, sizeof(id.base));
if (ret < 0) {
@@ -2615,6 +2617,7 @@ static struct sfp *sfp_alloc(struct device *dev)
return ERR_PTR(-ENOMEM);
sfp->dev = dev;
+ sfp->i2c_block_size = SFP_EEPROM_BLOCK_SIZE;
mutex_init(&sfp->sm_mutex);
mutex_init(&sfp->st_mutex);