* [PATCH] i3c: dw: make struct dw_i3c_cmd smaller @ 2026-08-13 4:46 Jisheng Zhang 2026-08-13 20:38 ` Frank Li 0 siblings, 1 reply; 4+ messages in thread From: Jisheng Zhang @ 2026-08-13 4:46 UTC (permalink / raw) To: Alexandre Belloni, Frank Li; +Cc: linux-i3c, linux-kernel The dw_i3c_cmd is dynamically allocated, make it smaller. For example on 64bit platforms, we reduce the size from 48 bytes to 32 bytes. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> --- drivers/i3c/master/dw-i3c-master.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c index 6ba84a97765f..d6f84f0f4c2d 100644 --- a/drivers/i3c/master/dw-i3c-master.c +++ b/drivers/i3c/master/dw-i3c-master.c @@ -247,10 +247,10 @@ struct dw_i3c_cmd { u32 cmd_lo; u32 cmd_hi; u16 tx_len; - const void *tx_buf; u16 rx_len; - void *rx_buf; u8 error; + const void *tx_buf; + void *rx_buf; }; struct dw_i3c_xfer { -- 2.51.0 -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] i3c: dw: make struct dw_i3c_cmd smaller 2026-08-13 4:46 [PATCH] i3c: dw: make struct dw_i3c_cmd smaller Jisheng Zhang @ 2026-08-13 20:38 ` Frank Li 2026-08-14 3:57 ` Jisheng Zhang 0 siblings, 1 reply; 4+ messages in thread From: Frank Li @ 2026-08-13 20:38 UTC (permalink / raw) To: Jisheng Zhang; +Cc: Alexandre Belloni, Frank Li, linux-i3c, linux-kernel On Thu, Aug 13, 2026 at 12:46:03PM +0800, Jisheng Zhang wrote: > The dw_i3c_cmd is dynamically allocated, make it smaller. For example > on 64bit platforms, we reduce the size from 48 bytes to 32 bytes. > > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > --- > drivers/i3c/master/dw-i3c-master.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c > index 6ba84a97765f..d6f84f0f4c2d 100644 > --- a/drivers/i3c/master/dw-i3c-master.c > +++ b/drivers/i3c/master/dw-i3c-master.c > @@ -247,10 +247,10 @@ struct dw_i3c_cmd { > u32 cmd_lo; > u32 cmd_hi; > u16 tx_len; > - const void *tx_buf; > u16 rx_len; only switch rx_len and tx_buf should be enough. otherwise there are data pad after u8 error. Frank > - void *rx_buf; > u8 error; > + const void *tx_buf; > + void *rx_buf; > }; > > struct dw_i3c_xfer { > -- > 2.51.0 > -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] i3c: dw: make struct dw_i3c_cmd smaller 2026-08-13 20:38 ` Frank Li @ 2026-08-14 3:57 ` Jisheng Zhang 2026-08-14 16:59 ` Frank Li 0 siblings, 1 reply; 4+ messages in thread From: Jisheng Zhang @ 2026-08-14 3:57 UTC (permalink / raw) To: Frank Li; +Cc: Alexandre Belloni, Frank Li, linux-i3c, linux-kernel On Thu, Aug 13, 2026 at 04:38:32PM -0400, Frank Li wrote: > On Thu, Aug 13, 2026 at 12:46:03PM +0800, Jisheng Zhang wrote: > > The dw_i3c_cmd is dynamically allocated, make it smaller. For example > > on 64bit platforms, we reduce the size from 48 bytes to 32 bytes. > > > > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > > --- > > drivers/i3c/master/dw-i3c-master.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c > > index 6ba84a97765f..d6f84f0f4c2d 100644 > > --- a/drivers/i3c/master/dw-i3c-master.c > > +++ b/drivers/i3c/master/dw-i3c-master.c > > @@ -247,10 +247,10 @@ struct dw_i3c_cmd { > > u32 cmd_lo; > > u32 cmd_hi; > > u16 tx_len; > > - const void *tx_buf; > > u16 rx_len; > > only switch rx_len and tx_buf should be enough. otherwise there are data > pad after u8 error. If we keep the error at the end of the struct, there's still padding after the u8 error. There's no big difference between current sol and only switch rx_len and tx_buf on 32bit platforms. But on 64bit platforms, the current version makes use of the pad to store the error, thus saves 8 byte more. Thanks > > Frank > > > - void *rx_buf; > > u8 error; > > + const void *tx_buf; > > + void *rx_buf; > > }; > > > > struct dw_i3c_xfer { > > -- > > 2.51.0 > > -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] i3c: dw: make struct dw_i3c_cmd smaller 2026-08-14 3:57 ` Jisheng Zhang @ 2026-08-14 16:59 ` Frank Li 0 siblings, 0 replies; 4+ messages in thread From: Frank Li @ 2026-08-14 16:59 UTC (permalink / raw) To: Jisheng Zhang; +Cc: Alexandre Belloni, Frank Li, linux-i3c, linux-kernel On Fri, Aug 14, 2026 at 11:57:24AM +0800, Jisheng Zhang wrote: > On Thu, Aug 13, 2026 at 04:38:32PM -0400, Frank Li wrote: > > On Thu, Aug 13, 2026 at 12:46:03PM +0800, Jisheng Zhang wrote: > > > The dw_i3c_cmd is dynamically allocated, make it smaller. For example > > > on 64bit platforms, we reduce the size from 48 bytes to 32 bytes. > > > > > > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > > > --- > > > drivers/i3c/master/dw-i3c-master.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c > > > index 6ba84a97765f..d6f84f0f4c2d 100644 > > > --- a/drivers/i3c/master/dw-i3c-master.c > > > +++ b/drivers/i3c/master/dw-i3c-master.c > > > @@ -247,10 +247,10 @@ struct dw_i3c_cmd { > > > u32 cmd_lo; > > > u32 cmd_hi; > > > u16 tx_len; > > > - const void *tx_buf; > > > u16 rx_len; > > > > only switch rx_len and tx_buf should be enough. otherwise there are data > > pad after u8 error. > > If we keep the error at the end of the struct, there's still padding > after the u8 error. > There's no big difference between current sol and only switch rx_len and > tx_buf on 32bit platforms. But on 64bit platforms, the current version > makes use of the pad to store the error, thus saves 8 byte more. Yes, I missed caculate. Reviewed-by: Frank Li <Frank.Li@nxp.com> > > Thanks > > > > Frank > > > > > - void *rx_buf; > > > u8 error; > > > + const void *tx_buf; > > > + void *rx_buf; > > > }; > > > > > > struct dw_i3c_xfer { > > > -- > > > 2.51.0 > > > -- linux-i3c mailing list linux-i3c@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-i3c ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-08-14 17:00 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-08-13 4:46 [PATCH] i3c: dw: make struct dw_i3c_cmd smaller Jisheng Zhang 2026-08-13 20:38 ` Frank Li 2026-08-14 3:57 ` Jisheng Zhang 2026-08-14 16:59 ` Frank Li
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