| Message ID | 20171127210613.9140-1-brgl@bgdev.pl |
|---|---|
| State | Accepted |
| Delegated to: | Bartosz Golaszewski |
| Headers | show |
| Series | eeprom: at24: correctly set the size for at24mac402 | expand |
On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote: > There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down > the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, > making it impossible to read it all. > > Fix it by manually adjusting the value in probe(). > > This patch contains a temporary fix that is suitable for stable > branches. Eventually we'll probably remove the call to ilog2() while > converting the magic values to actual structs. > + /* > + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while > + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. > + * > + * Eventually we'll get rid of the magic values altoghether in favor of > + * real structs, but for now just manually set the right size. > + */ > + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) I didn't check, but do we need to test for len == 4 at all? > + chip.byte_len = 6;
2017-11-28 11:25 GMT+01:00 Andy Shevchenko <andy.shevchenko@gmail.com>: > On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote: >> There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down >> the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, >> making it impossible to read it all. >> >> Fix it by manually adjusting the value in probe(). >> >> This patch contains a temporary fix that is suitable for stable >> branches. Eventually we'll probably remove the call to ilog2() while >> converting the magic values to actual structs. > >> + /* >> + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while >> + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. >> + * >> + * Eventually we'll get rid of the magic values altoghether in favor of >> + * real structs, but for now just manually set the right size. >> + */ >> + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) > > I didn't check, but do we need to test for len == 4 at all? > >> + chip.byte_len = 6; > > -- > With Best Regards, > Andy Shevchenko Yes, because the fix is only relevant for at24mac402 whose MAC byte array is 6 bytes long, while the one in at24mac602 is 8 bytes and the driver doesn't truncate the byte_len for it. Thanks, Bartosz
On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote: > There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down > the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, > making it impossible to read it all. > > Fix it by manually adjusting the value in probe(). > > This patch contains a temporary fix that is suitable for stable > branches. Eventually we'll probably remove the call to ilog2() while > converting the magic values to actual structs. > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > Cc: stable@vger.kernel.org > Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series") > Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl> > --- > drivers/misc/eeprom/at24.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c > index e0b4b36ef010..783244b485cc 100644 > --- a/drivers/misc/eeprom/at24.c > +++ b/drivers/misc/eeprom/at24.c > @@ -730,6 +730,16 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) > dev_warn(&client->dev, > "page_size looks suspicious (no power of 2)!\n"); > > + /* > + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while > + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. > + * > + * Eventually we'll get rid of the magic values altoghether in favor of > + * real structs, but for now just manually set the right size. > + */ > + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) > + chip.byte_len = 6; > + > /* Use I2C operations unless we're stuck with SMBus extensions. */ > if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { > if (chip.flags & AT24_FLAG_ADDR16) > -- > 2.15.0 >
Am 28.11.2017 um 13:09 schrieb Andy Shevchenko: > On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote: >> There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down >> the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, >> making it impossible to read it all. >> >> Fix it by manually adjusting the value in probe(). >> >> This patch contains a temporary fix that is suitable for stable >> branches. Eventually we'll probably remove the call to ilog2() while >> converting the magic values to actual structs. >> > > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > Looks good also to me. >> Cc: stable@vger.kernel.org >> Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series") >> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl> >> --- >> drivers/misc/eeprom/at24.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c >> index e0b4b36ef010..783244b485cc 100644 >> --- a/drivers/misc/eeprom/at24.c >> +++ b/drivers/misc/eeprom/at24.c >> @@ -730,6 +730,16 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) >> dev_warn(&client->dev, >> "page_size looks suspicious (no power of 2)!\n"); >> >> + /* >> + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while >> + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. >> + * >> + * Eventually we'll get rid of the magic values altoghether in favor of >> + * real structs, but for now just manually set the right size. >> + */ >> + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) >> + chip.byte_len = 6; >> + >> /* Use I2C operations unless we're stuck with SMBus extensions. */ >> if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { >> if (chip.flags & AT24_FLAG_ADDR16) >> -- >> 2.15.0 >> > > >
On 28.11.2017 12:44, Bartosz Golaszewski wrote: > 2017-11-28 11:25 GMT+01:00 Andy Shevchenko <andy.shevchenko@gmail.com>: >> On Mon, Nov 27, 2017 at 11:06 PM, Bartosz Golaszewski <brgl@bgdev.pl> wrote: >>> There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down >>> the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, >>> making it impossible to read it all. >>> >>> Fix it by manually adjusting the value in probe(). >>> >>> This patch contains a temporary fix that is suitable for stable >>> branches. Eventually we'll probably remove the call to ilog2() while >>> converting the magic values to actual structs. >> >>> + /* >>> + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while >>> + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. >>> + * >>> + * Eventually we'll get rid of the magic values altoghether in favor of >>> + * real structs, but for now just manually set the right size. >>> + */ >>> + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) >> >> I didn't check, but do we need to test for len == 4 at all? >> >>> + chip.byte_len = 6; >> >> -- >> With Best Regards, >> Andy Shevchenko > > Yes, because the fix is only relevant for at24mac402 whose MAC byte > array is 6 bytes long, while the one in at24mac602 is 8 bytes and the > driver doesn't truncate the byte_len for it. From my point of view, I think all chips in at24_ids[] array should be checked about restrictions regarding the size truncation (especially the ones from the initial commit: "2b7a5056a0a7ff17d5d2 i2c: New-style EEPROM driver using device IDs" which introduces AT24_DEVICE_MAGIC() macro) and if none of them has such restrictions we should get rid of the ilog2() restrictions. Just my 2 cents... Claudiu > > Thanks, > Bartosz >
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c index e0b4b36ef010..783244b485cc 100644 --- a/drivers/misc/eeprom/at24.c +++ b/drivers/misc/eeprom/at24.c @@ -730,6 +730,16 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) dev_warn(&client->dev, "page_size looks suspicious (no power of 2)!\n"); + /* + * REVISIT: the size of the EUI-48 byte array is 6 in at24mac402, while + * the call to ilog2() in AT24_DEVICE_MAGIC() rounds it down to 4. + * + * Eventually we'll get rid of the magic values altoghether in favor of + * real structs, but for now just manually set the right size. + */ + if (chip.flags & AT24_FLAG_MAC && chip.byte_len == 4) + chip.byte_len = 6; + /* Use I2C operations unless we're stuck with SMBus extensions. */ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { if (chip.flags & AT24_FLAG_ADDR16)
There's an ilog2() expansion in AT24_DEVICE_MAGIC() which rounds down the actual size of EUI-48 byte array in at24mac402 eeproms to 4 from 6, making it impossible to read it all. Fix it by manually adjusting the value in probe(). This patch contains a temporary fix that is suitable for stable branches. Eventually we'll probably remove the call to ilog2() while converting the magic values to actual structs. Cc: stable@vger.kernel.org Fixes: 0b813658c115 ("eeprom: at24: add support for at24mac series") Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl> --- drivers/misc/eeprom/at24.c | 10 ++++++++++ 1 file changed, 10 insertions(+)