| Message ID | 20250121110756.214714-1-billy_tsai@aspeedtech.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/2] i3c: Remove the const qualifier from i2c_msg pointer in i2c_xfers API | expand |
On Tue, Jan 21, 2025 at 07:07:55PM +0800, Billy Tsai wrote: > The change is necessary to enable the use of the > `i2c_get_dma_safe_msg_buf()` API, which requires a non-const > `struct i2c_msg *` to operate. The `i2c_get_dma_safe_msg_buf()` function > ensures safe handling of I2C messages when using DMA, making it essential > for scenarios where DMA transfers are involved. By removing the `const` > qualifier, this patch allows drivers to prepare and manage DMA-safe > buffers directly. > > Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com> Makes sense to me: Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Good Change Billy. Thanks for bringing this to i3c. On 1/21/2025 4:37 PM, Billy Tsai wrote: > The change is necessary to enable the use of the > `i2c_get_dma_safe_msg_buf()` API, which requires a non-const > `struct i2c_msg *` to operate. The `i2c_get_dma_safe_msg_buf()` function > ensures safe handling of I2C messages when using DMA, making it essential > for scenarios where DMA transfers are involved. By removing the `const` > qualifier, this patch allows drivers to prepare and manage DMA-safe > buffers directly. > > Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com> > --- > drivers/i3c/master/dw-i3c-master.c | 2 +- > drivers/i3c/master/i3c-master-cdns.c | 2 +- > drivers/i3c/master/mipi-i3c-hci/core.c | 2 +- > drivers/i3c/master/svc-i3c-master.c | 2 +- > include/linux/i3c/master.h | 2 +- > 5 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c > index d09ea5b6467c..54c7d86997d5 100644 > --- a/drivers/i3c/master/dw-i3c-master.c > +++ b/drivers/i3c/master/dw-i3c-master.c > @@ -1079,7 +1079,7 @@ static void dw_i3c_master_detach_i3c_dev(struct i3c_dev_desc *dev) > } > > static int dw_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, > - const struct i2c_msg *i2c_xfers, > + struct i2c_msg *i2c_xfers, what we need is only i2c_xfers->buf to be DMA-safe, not the *i2c_xfers. Right ? > int i2c_nxfers) > { > struct dw_i3c_i2c_dev_data *data = i2c_dev_get_master_data(dev); > diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c > index 8d69a34986d9..c9e4c129454c 100644 > --- a/drivers/i3c/master/i3c-master-cdns.c > +++ b/drivers/i3c/master/i3c-master-cdns.c > @@ -813,7 +813,7 @@ static int cdns_i3c_master_priv_xfers(struct i3c_dev_desc *dev, > } > > static int cdns_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, > - const struct i2c_msg *xfers, int nxfers) > + struct i2c_msg *xfers, int nxfers) > { > struct i3c_master_controller *m = i2c_dev_get_master(dev); > struct cdns_i3c_master *master = to_cdns_i3c_master(m); we only need to use i2c_get_dma_safe_msg_buf() for the xfers[i].buf being used inside the driver as a protection ? Also I guess same change is required for all the vendor drivers. But Not sure if it's feasible with this patch ? > diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c > index e6e482a259b4..a408feac3e9e 100644 > --- a/drivers/i3c/master/mipi-i3c-hci/core.c > +++ b/drivers/i3c/master/mipi-i3c-hci/core.c > @@ -367,7 +367,7 @@ static int i3c_hci_priv_xfers(struct i3c_dev_desc *dev, > } > > static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev, > - const struct i2c_msg *i2c_xfers, int nxfers) > + struct i2c_msg *i2c_xfers, int nxfers) > { > struct i3c_master_controller *m = i2c_dev_get_master(dev); > struct i3c_hci *hci = to_i3c_hci(m); > diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c > index c1ee3828e7ee..24bd701b5de0 100644 > --- a/drivers/i3c/master/svc-i3c-master.c > +++ b/drivers/i3c/master/svc-i3c-master.c > @@ -1584,7 +1584,7 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev, > } > > static int svc_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, > - const struct i2c_msg *xfers, > + struct i2c_msg *xfers, > int nxfers) > { > struct i3c_master_controller *m = i2c_dev_get_master(dev); > diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h > index 12d532b012c5..c67922ece617 100644 > --- a/include/linux/i3c/master.h > +++ b/include/linux/i3c/master.h > @@ -475,7 +475,7 @@ struct i3c_master_controller_ops { > int (*attach_i2c_dev)(struct i2c_dev_desc *dev); > void (*detach_i2c_dev)(struct i2c_dev_desc *dev); > int (*i2c_xfers)(struct i2c_dev_desc *dev, > - const struct i2c_msg *xfers, int nxfers); > + struct i2c_msg *xfers, int nxfers); > int (*request_ibi)(struct i3c_dev_desc *dev, > const struct i3c_ibi_setup *req); > void (*free_ibi)(struct i3c_dev_desc *dev);
> what we need is only i2c_xfers->buf to be DMA-safe, not the *i2c_xfers. > Right ? Yes. > Also I guess same change is required for all the vendor drivers. But Not > sure if it's feasible with this patch ? I also wondered if the I3C core should maybe provide this, but then I saw that currently only the mipi-hci driver uses DMA and concluded that per-driver is better. At least for now.
On 2025-01-21 19:07:55+0800, Billy Tsai wrote: > The change is necessary to enable the use of the > `i2c_get_dma_safe_msg_buf()` API, which requires a non-const > `struct i2c_msg *` to operate. The `i2c_get_dma_safe_msg_buf()` function > ensures safe handling of I2C messages when using DMA, making it essential > for scenarios where DMA transfers are involved. By removing the `const` > qualifier, this patch allows drivers to prepare and manage DMA-safe > buffers directly. Why not modify i2c_get_dma_safe_msg_buf() to accept 'const struct i2c_msg' instead? > Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com> > --- > drivers/i3c/master/dw-i3c-master.c | 2 +- > drivers/i3c/master/i3c-master-cdns.c | 2 +- > drivers/i3c/master/mipi-i3c-hci/core.c | 2 +- > drivers/i3c/master/svc-i3c-master.c | 2 +- > include/linux/i3c/master.h | 2 +- > 5 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c index d09ea5b6467c..54c7d86997d5 100644 --- a/drivers/i3c/master/dw-i3c-master.c +++ b/drivers/i3c/master/dw-i3c-master.c @@ -1079,7 +1079,7 @@ static void dw_i3c_master_detach_i3c_dev(struct i3c_dev_desc *dev) } static int dw_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, - const struct i2c_msg *i2c_xfers, + struct i2c_msg *i2c_xfers, int i2c_nxfers) { struct dw_i3c_i2c_dev_data *data = i2c_dev_get_master_data(dev); diff --git a/drivers/i3c/master/i3c-master-cdns.c b/drivers/i3c/master/i3c-master-cdns.c index 8d69a34986d9..c9e4c129454c 100644 --- a/drivers/i3c/master/i3c-master-cdns.c +++ b/drivers/i3c/master/i3c-master-cdns.c @@ -813,7 +813,7 @@ static int cdns_i3c_master_priv_xfers(struct i3c_dev_desc *dev, } static int cdns_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, - const struct i2c_msg *xfers, int nxfers) + struct i2c_msg *xfers, int nxfers) { struct i3c_master_controller *m = i2c_dev_get_master(dev); struct cdns_i3c_master *master = to_cdns_i3c_master(m); diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c index e6e482a259b4..a408feac3e9e 100644 --- a/drivers/i3c/master/mipi-i3c-hci/core.c +++ b/drivers/i3c/master/mipi-i3c-hci/core.c @@ -367,7 +367,7 @@ static int i3c_hci_priv_xfers(struct i3c_dev_desc *dev, } static int i3c_hci_i2c_xfers(struct i2c_dev_desc *dev, - const struct i2c_msg *i2c_xfers, int nxfers) + struct i2c_msg *i2c_xfers, int nxfers) { struct i3c_master_controller *m = i2c_dev_get_master(dev); struct i3c_hci *hci = to_i3c_hci(m); diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c index c1ee3828e7ee..24bd701b5de0 100644 --- a/drivers/i3c/master/svc-i3c-master.c +++ b/drivers/i3c/master/svc-i3c-master.c @@ -1584,7 +1584,7 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev, } static int svc_i3c_master_i2c_xfers(struct i2c_dev_desc *dev, - const struct i2c_msg *xfers, + struct i2c_msg *xfers, int nxfers) { struct i3c_master_controller *m = i2c_dev_get_master(dev); diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 12d532b012c5..c67922ece617 100644 --- a/include/linux/i3c/master.h +++ b/include/linux/i3c/master.h @@ -475,7 +475,7 @@ struct i3c_master_controller_ops { int (*attach_i2c_dev)(struct i2c_dev_desc *dev); void (*detach_i2c_dev)(struct i2c_dev_desc *dev); int (*i2c_xfers)(struct i2c_dev_desc *dev, - const struct i2c_msg *xfers, int nxfers); + struct i2c_msg *xfers, int nxfers); int (*request_ibi)(struct i3c_dev_desc *dev, const struct i3c_ibi_setup *req); void (*free_ibi)(struct i3c_dev_desc *dev);
The change is necessary to enable the use of the `i2c_get_dma_safe_msg_buf()` API, which requires a non-const `struct i2c_msg *` to operate. The `i2c_get_dma_safe_msg_buf()` function ensures safe handling of I2C messages when using DMA, making it essential for scenarios where DMA transfers are involved. By removing the `const` qualifier, this patch allows drivers to prepare and manage DMA-safe buffers directly. Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com> --- drivers/i3c/master/dw-i3c-master.c | 2 +- drivers/i3c/master/i3c-master-cdns.c | 2 +- drivers/i3c/master/mipi-i3c-hci/core.c | 2 +- drivers/i3c/master/svc-i3c-master.c | 2 +- include/linux/i3c/master.h | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-)