Hi, Ben Thanks for your suggestion. On Thu, Feb 4, 2010 at 3:37 PM, Ben Dooks <ben-linux@xxxxxxxxx> wrote: > > On Thu, Feb 04, 2010 at 02:04:03PM +0800, zhangfei gao wrote: > > Hi, Jean > > > > > > We found type of i2c_msg.len is __u16, while parameter count in > > i2c_master_send is int. > > The mismatch will truncate count from int to u16. > > For example we downloading firmware which is more than 64K (64K+8) via i2c, > > i2c would transfer u16 (8 bytes) in fact. > > I would be wary of changing the i2c_msg structure as this is exported to > userspace. > > > I think a better fix would be to test the count parameter to i2c_master_send > and return something like EMSGSIZE to inform the user it is too long. > > If you really want i2c transfers of 64K and above, then you might have to > add a new struct i2c_msg and update all the callsites to use it. Either that > or chain a set of msgs together and pass them to the i2c controller in one > go. > > Please discuss on the i2c list. > 1. Both i2c_master_send and i2c_msg are exported in include/linux/i2c.h. 2. Both i2c_master_send and i2c_master_recv supposed to support int count, is it suitable to return error when count is bigger than 64K? 3. It may impact a lot if adding new structure :) include/linux/i2c.h extern int i2c_master_send(struct i2c_client *client, const char *buf, int count); extern int i2c_master_recv(struct i2c_client *client, char *buf, int count); Thansk Zhangfei > > >From 69ec7599bf0fa28441281be1df76a2f573bb9127 Mon Sep 17 00:00:00 2001 > > From: Zhangfei Gao <zgao6@xxxxxxxxxxx> > > Date: Fri, 5 Feb 2010 05:12:19 +0800 > > Subject: [PATCH] i2c: i2c_msg.len modify to __u32 type > > > > int i2c_master_send(struct i2c_client *client,const char *buf ,int > > count) > > { > > ~ > > msg.len = count; > > ~ > > } > > Parameter count would truncate from int to __u16 > > > > Signed-off-by: Zhangfei Gao <zgao6@xxxxxxxxxxx> > > --- > > include/linux/i2c.h | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/include/linux/i2c.h b/include/linux/i2c.h > > index 57d41b0..4769ce9 100644 > > --- a/include/linux/i2c.h > > +++ b/include/linux/i2c.h > > @@ -491,7 +491,7 @@ struct i2c_msg { > > #define I2C_M_IGNORE_NAK 0x1000 /* if I2C_FUNC_PROTOCOL_MANGLING */ > > #define I2C_M_NO_RD_ACK 0x0800 /* if I2C_FUNC_PROTOCOL_MANGLING > > */ > > #define I2C_M_RECV_LEN 0x0400 /* length will be first received > > byte */ > > - __u16 len; /* msg length */ > > + __u32 len; /* msg length */ > > __u8 *buf; /* pointer to msg data */ > > }; > > > > -- > > 1.6.0.4 > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > > > -- > -- > Ben > > Q: What's a light-year? > A: One-third less calories than a regular year. > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html