On Thu, Aug 15, 2024 at 08:57:18AM +0200, Ahmad Fatoum wrote: > Hello Tomas, > > On 15.08.24 07:53, Tomas Marek wrote: > > Hello Ahmad, > > > > Thanks for maintenance of the Barebox EFI. > > > > On Wed, Aug 14, 2024 at 11:24:23AM +0200, Ahmad Fatoum wrote: > >> I2C message length is 16 bit, so doing a 64-bit division is overkill. > >> Let's remove the cast and just rely on the usual integer promotion > >> to 32-bit. > >> > >> Cc: Tomas Marek <tomas.marek@xxxxxxxxx> > >> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > >> --- > >> drivers/i2c/busses/i2c-efi.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/i2c/busses/i2c-efi.c b/drivers/i2c/busses/i2c-efi.c > >> index 5f6cc0eed28e..a666a28fab51 100644 > >> --- a/drivers/i2c/busses/i2c-efi.c > >> +++ b/drivers/i2c/busses/i2c-efi.c > >> @@ -114,7 +114,7 @@ static unsigned int efi_i2c_msg_op_cnt(const struct efi_i2c_priv *i2c_priv, > >> > >> max_len = efi_i2c_max_len(i2c_priv, msg); > >> > >> - return ((u64)msg->len + max_len - 1) / max_len; > >> + return (msg->len + max_len - 1) / max_len; > > > > The issue here is that max_len, which represents the MaximumReceiveBytes > > or MaximumTransmitBytes in EFI I2C capabilities, is 32-bit. In some EFI > > implementations (including the one I use), the EFI I2C MaximumReceiveBytes > > and MaximumTransmitBytes are set to the maximum value (0xFFFFFFFF). This > > causes msg->len + max_len - 1 to overflow, leading to an incorrect number > > of returned operations. To address this, the msg->len is extended to 64 bits. > > Thanks for the info. See the patch I just Cc'd you on. > > @Sascha, can you drop this one patch again? Ok, reverted it. Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
