| Message ID | 20191112203132.163306-4-dmitry.torokhov@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Use void pointers instead of char in I2C transfer APIs | expand |
Hi Dmitry, On 12/11/19 21:31, Dmitry Torokhov wrote: > When copying memory from one buffer to another, instead of open-coding > loops with byte-by-byte copies let's use memcpy() which might be a bit > faster and makes intent more clear. Good idea! Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>
Hello Dmitry, On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote: > When copying memory from one buffer to another, instead of open-coding > loops with byte-by-byte copies let's use memcpy() which might be a bit > faster and makes intent more clear. > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > --- > > Changes in v3: > - new patch using memcpy() for moving data around > > drivers/i2c/i2c-core-smbus.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > index 7b4e2270eeda1..bbafdd3b1b114 100644 > --- a/drivers/i2c/i2c-core-smbus.c > +++ b/drivers/i2c/i2c-core-smbus.c > @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, > } > > i2c_smbus_try_get_dmabuf(&msg[0], command); > - for (i = 1; i < msg[0].len; i++) > - msg[0].buf[i] = data->block[i - 1]; > + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1); Can it happen that msg[0].len is zero? > } > break; > case I2C_SMBUS_BLOCK_PROC_CALL: Best regards Uwe
On Mon, Nov 18, 2019 at 08:47:57AM +0100, Uwe Kleine-König wrote: > Hello Dmitry, > > On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote: > > When copying memory from one buffer to another, instead of open-coding > > loops with byte-by-byte copies let's use memcpy() which might be a bit > > faster and makes intent more clear. > > > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > > > --- > > > > Changes in v3: > > - new patch using memcpy() for moving data around > > > > drivers/i2c/i2c-core-smbus.c | 15 +++++---------- > > 1 file changed, 5 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > > index 7b4e2270eeda1..bbafdd3b1b114 100644 > > --- a/drivers/i2c/i2c-core-smbus.c > > +++ b/drivers/i2c/i2c-core-smbus.c > > @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, > > } > > > > i2c_smbus_try_get_dmabuf(&msg[0], command); > > - for (i = 1; i < msg[0].len; i++) > > - msg[0].buf[i] = data->block[i - 1]; > > + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1); > > Can it happen that msg[0].len is zero? No, it can not, because of the "msg[0].len = data->block[0] + 2;" line above. Thanks.
On Mon, Nov 18, 2019 at 12:09:39AM -0800, Dmitry Torokhov wrote: > On Mon, Nov 18, 2019 at 08:47:57AM +0100, Uwe Kleine-König wrote: > > Hello Dmitry, > > > > On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote: > > > When copying memory from one buffer to another, instead of open-coding > > > loops with byte-by-byte copies let's use memcpy() which might be a bit > > > faster and makes intent more clear. > > > > > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > > > > > --- > > > > > > Changes in v3: > > > - new patch using memcpy() for moving data around > > > > > > drivers/i2c/i2c-core-smbus.c | 15 +++++---------- > > > 1 file changed, 5 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > > > index 7b4e2270eeda1..bbafdd3b1b114 100644 > > > --- a/drivers/i2c/i2c-core-smbus.c > > > +++ b/drivers/i2c/i2c-core-smbus.c > > > @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, > > > } > > > > > > i2c_smbus_try_get_dmabuf(&msg[0], command); > > > - for (i = 1; i < msg[0].len; i++) > > > - msg[0].buf[i] = data->block[i - 1]; > > > + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1); > > > > Can it happen that msg[0].len is zero? > > No, it can not, because of the "msg[0].len = data->block[0] + 2;" line > above. OK, and as passing data with data->block[0] = 254 also makes the code do strange things already without your patch. I now also checked the other conversions for similar problems and didn't find any. So: Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Best regards Uwe
On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote: > When copying memory from one buffer to another, instead of open-coding > loops with byte-by-byte copies let's use memcpy() which might be a bit > faster and makes intent more clear. > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > This one I like very much! Applied to for-next, thanks!
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 7b4e2270eeda1..bbafdd3b1b114 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, } i2c_smbus_try_get_dmabuf(&msg[0], command); - for (i = 1; i < msg[0].len; i++) - msg[0].buf[i] = data->block[i - 1]; + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1); } break; case I2C_SMBUS_BLOCK_PROC_CALL: @@ -413,8 +412,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, msg[0].len = data->block[0] + 2; i2c_smbus_try_get_dmabuf(&msg[0], command); - for (i = 1; i < msg[0].len; i++) - msg[0].buf[i] = data->block[i - 1]; + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1); msg[1].flags |= I2C_M_RECV_LEN; msg[1].len = 1; /* block length will be added by @@ -436,8 +434,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, msg[0].len = data->block[0] + 1; i2c_smbus_try_get_dmabuf(&msg[0], command); - for (i = 1; i <= data->block[0]; i++) - msg[0].buf[i] = data->block[i]; + memcpy(msg[0].buf + 1, data->block + 1, data->block[0]); } break; default: @@ -489,13 +486,11 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, data->word = get_unaligned_le16(msgbuf1); break; case I2C_SMBUS_I2C_BLOCK_DATA: - for (i = 0; i < data->block[0]; i++) - data->block[i + 1] = msg[1].buf[i]; + memcpy(data->block + 1, msg[1].buf, data->block[0]); break; case I2C_SMBUS_BLOCK_DATA: case I2C_SMBUS_BLOCK_PROC_CALL: - for (i = 0; i < msg[1].buf[0] + 1; i++) - data->block[i] = msg[1].buf[i]; + memcpy(data->block, msg[1].buf, msg[1].buf[0] + 1); break; }
When copying memory from one buffer to another, instead of open-coding loops with byte-by-byte copies let's use memcpy() which might be a bit faster and makes intent more clear. Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- Changes in v3: - new patch using memcpy() for moving data around drivers/i2c/i2c-core-smbus.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-)