Re: [PATCHv2] usb: typec: tps6598x: handle block writes separately with plain-I2C adapters

[Nikolaus Voss]

On Wed, 20 Feb 2019, Guenter Roeck wrote:
> On 2/20/19 4:57 AM, Nikolaus Voss wrote:
> > Commit 1a2f474d328f handles block _reads_ separately with plain-I2C
> > adapters, but the problem described with regmap-i2c not handling
> > SMBus block transfers (i.e. read and writes) correctly also exists
> > with writes.
> >
> > As workaround, this patch adds a block write function the same way
> > 1a2f474d328f adds a block read function.
> >
> > Fixes: 1a2f474d328f ("usb: typec: tps6598x: handle block reads separately 
> > with plain-I2C adapters")
> > Fixes: 0a4c005bd171 ("usb: typec: driver for TI TPS6598x USB Power Delivery 
> > controllers")
> > Signed-off-by: Nikolaus Voss <nikolaus.voss@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> > v2: fix tps6598x_exec_cmd also
> > ---
> >   drivers/usb/typec/tps6598x.c | 26 ++++++++++++++++++++------
> >   1 file changed, 20 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c
> > index c84c8c189e90..c54b73fb2a2f 100644
> > --- a/drivers/usb/typec/tps6598x.c
> > +++ b/drivers/usb/typec/tps6598x.c
> > @@ -110,6 +110,20 @@ tps6598x_block_read(struct tps6598x *tps, u8 reg, void 
> > *val, size_t len)
> >   	return 0;
> >   }
> >   +static int tps6598x_block_write(struct tps6598x *tps, u8 reg,
> > +				void *val, size_t len)
> > +{
> > +	u8 data[len + 1];
> > +
>
> You should use TPS_MAX_LEN + 1 here to avoid the variable length array.
> See upstream commit 0bb95f80a38f8 ("Makefile: Globally enable VLA warning")
> and 8d361fa2c29dc ("usb: typec: tps6598x: Remove VLA usage"). Not sure if
> the WARN_ON introduced by 8d361fa2c29dc is really needed; I dislike
> unnecessary runtime checks.

Thanks for the pointer, I fixed this...

Nikolaus