| Message ID | cover.1680602387.git.lmorhet@kalrayinc.com |
|---|---|
| Headers | show |
| Series | Fixes for the mcp2221 gpiochip get_* calls | expand |
On Apr 04 2023, Louis Morhet wrote: > The mcp2221 HID driver exposes a gpiochip device. > While gpioset seemed to work fine, gpioget always returned 1 on all 4 > GPIOs of the component (0x01 for input in the field "direction", > according to the documentation). > > This patch series addresses this issue by fixing the order of the fields > in the driver's representation of the chip answer, and adding > consistency to the way the callbacks prepare their command and the way > the hid event handler gets these fields. > The set callbacks use a similar mechanism, but work for now because > setting a direction/value only requires gpio-specific positioning in the > command preparation, and not in the raw_event handler. As you should have seen in the automatic replied, I took that series in because it seems to fix a rather worrying bug. > > The core of this issue being a discrepancy in the way the command and > the answer fetch their fields of interest, I would also like to ask if > we should uniformize a bit the way this driver handles gpio, and how. > I thought about several possible implementations for that: > Use mcp->gp_idx as the base offset of the gpio for set too, and modify > the raw_event handler to fetch all relevant data based on that; or set > the buffers in the mcp structure as unions of the various commands > handled and use gp_idx simply as the gpio index to access relevant data > directly from the structured representation everywhere; or go back to ye > old defines to ensure portability... Honestly, it's hard to make a choice here. You haven't got a replied from the other mcp2221 folks in almost 10 days so I am not sure you'll get feedback directly. May I suggest that you work on any one of these idea, and then submit a series? Generally, having the code ready makes it way easier to decide if this is a good solution or not, while having 3 different vague suggestions makes it hard to see the implications of them. Also, just a side note, this driver is very limited in term of scope, as it only touches one dedicated device. Which means that whatever solution feels the more elegant to you has a good chance of being accepted :) Cheers, Benjamin > > Louis Morhet (2): > HID: mcp2221: fix report layout for gpio get > HID: mcp2221: fix get and get_direction for gpio > > drivers/hid/hid-mcp2221.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > -- > 2.17.1 > > > > >
On Thu, Apr 13, 2023 at 04:49:13PM +0200, Benjamin Tissoires wrote: > As you should have seen in the automatic replied, I took that series in > because it seems to fix a rather worrying bug. Thanks! > Also, just a side note, this driver is very limited in term of scope, as > it only touches one dedicated device. Which means that whatever solution > feels the more elegant to you has a good chance of being accepted :) Well, using a struct to describe the layout of a message seems more elegant; but if I'm not mistaken, taking offsets of fields in a packed struct is UB... so I was surprised to even see that in Linux, that's why I was wondering if I should pursue in that direction. -- Louis