Re: [PATCH v4] HID: core: check whether Usage Page item is after Usage ID items

[Candle Sun <candlesea@gmail.com>]

Jiri & Benjamin,
Do you have some futher advice on this patch?
Can the patch be merged?

Regards,
Candle

On Tue, Oct 22, 2019 at 10:22 PM Candle Sun <candlesea@gmail.com> wrote:
>
> From: Candle Sun <candle.sun@unisoc.com>
>
> Upstream commit 58e75155009c ("HID: core: move Usage Page concatenation
> to Main item") adds support for Usage Page item after Usage ID items
> (such as keyboards manufactured by Primax).
>
> Usage Page concatenation in Main item works well for following report
> descriptor patterns:
>
>     USAGE_PAGE (Keyboard)                   05 07
>     USAGE_MINIMUM (Keyboard LeftControl)    19 E0
>     USAGE_MAXIMUM (Keyboard Right GUI)      29 E7
>     LOGICAL_MINIMUM (0)                     15 00
>     LOGICAL_MAXIMUM (1)                     25 01
>     REPORT_SIZE (1)                         75 01
>     REPORT_COUNT (8)                        95 08
>     INPUT (Data,Var,Abs)                    81 02
>
> -------------
>
>     USAGE_MINIMUM (Keyboard LeftControl)    19 E0
>     USAGE_MAXIMUM (Keyboard Right GUI)      29 E7
>     LOGICAL_MINIMUM (0)                     15 00
>     LOGICAL_MAXIMUM (1)                     25 01
>     REPORT_SIZE (1)                         75 01
>     REPORT_COUNT (8)                        95 08
>     USAGE_PAGE (Keyboard)                   05 07
>     INPUT (Data,Var,Abs)                    81 02
>
> But it makes the parser act wrong for the following report
> descriptor pattern(such as some Gamepads):
>
>     USAGE_PAGE (Button)                     05 09
>     USAGE (Button 1)                        09 01
>     USAGE (Button 2)                        09 02
>     USAGE (Button 4)                        09 04
>     USAGE (Button 5)                        09 05
>     USAGE (Button 7)                        09 07
>     USAGE (Button 8)                        09 08
>     USAGE (Button 14)                       09 0E
>     USAGE (Button 15)                       09 0F
>     USAGE (Button 13)                       09 0D
>     USAGE_PAGE (Consumer Devices)           05 0C
>     USAGE (Back)                            0a 24 02
>     USAGE (HomePage)                        0a 23 02
>     LOGICAL_MINIMUM (0)                     15 00
>     LOGICAL_MAXIMUM (1)                     25 01
>     REPORT_SIZE (1)                         75 01
>     REPORT_COUNT (11)                       95 0B
>     INPUT (Data,Var,Abs)                    81 02
>
> With Usage Page concatenation in Main item, parser recognizes all the
> 11 Usages as consumer keys, it is not the HID device's real intention.
>
> This patch checks whether Usage Page is really defined after Usage ID
> items by comparing usage page using status.
>
> Usage Page concatenation on currently defined Usage Page will always
> do in local parsing when Usage ID items encountered.
>
> When Main item is parsing, concatenation will do again with last
> defined Usage Page if this page has not been used in the previous
> usages concatenation.
>
> Signed-off-by: Candle Sun <candle.sun@unisoc.com>
> Signed-off-by: Nianfu Bai <nianfu.bai@unisoc.com>
> ---
> Changes in v4:
> - Fix v3 introduced BUG in hid_add_usage()
> - Add checking logic to replace usage_page_last member
> - Update patch description
>
> Changes in v3:
> - Rework the GET_COMPLETE_USAGE macro as static complete_usage()
>   function
> - Add some code comments for usage_page_last
>
> Changes in v2:
> - Update patch title
> - Add GET_COMPLETE_USAGE macro
> - Change the logic of checking whether to concatenate usage page again
>   in main parsing
> ---
>  drivers/hid/hid-core.c | 51 +++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 3eaee2c37931..c18ed7180b07 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -211,6 +211,18 @@ static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
>         return 0; /* we know nothing about this usage type */
>  }
>
> +/*
> + * Concatenate usage which defines 16 bits or less with the
> + * currently defined usage page to form a 32 bit usage
> + */
> +
> +static void complete_usage(struct hid_parser *parser, unsigned int index)
> +{
> +       parser->local.usage[index] &= 0xFFFF;
> +       parser->local.usage[index] |=
> +               (parser->global.usage_page & 0xFFFF) << 16;
> +}
> +
>  /*
>   * Add a usage to the temporary parser table.
>   */
> @@ -222,6 +234,14 @@ static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
>                 return -1;
>         }
>         parser->local.usage[parser->local.usage_index] = usage;
> +
> +       /*
> +        * If Usage item only includes usage id, concatenate it with
> +        * currently defined usage page
> +        */
> +       if (size <= 2)
> +               complete_usage(parser, parser->local.usage_index);
> +
>         parser->local.usage_size[parser->local.usage_index] = size;
>         parser->local.collection_index[parser->local.usage_index] =
>                 parser->collection_stack_ptr ?
> @@ -543,13 +563,32 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
>   * usage value."
>   */
>
> -static void hid_concatenate_usage_page(struct hid_parser *parser)
> +static void hid_concatenate_last_usage_page(struct hid_parser *parser)
>  {
>         int i;
> +       unsigned int usage_page;
> +       unsigned int current_page;
>
> -       for (i = 0; i < parser->local.usage_index; i++)
> -               if (parser->local.usage_size[i] <= 2)
> -                       parser->local.usage[i] += parser->global.usage_page << 16;
> +       if (!parser->local.usage_index)
> +               return;
> +
> +       usage_page = parser->global.usage_page;
> +
> +       /*
> +        * Concatenate usage page again only if last declared Usage Page
> +        * has not been already used in previous usages concatenation
> +        */
> +       for (i = parser->local.usage_index - 1; i >= 0; i--) {
> +               if (parser->local.usage_size[i] > 2)
> +                       /* Ignore extended usages */
> +                       continue;
> +
> +               current_page = parser->local.usage[i] >> 16;
> +               if (current_page == usage_page)
> +                       break;
> +
> +               complete_usage(parser, i);
> +       }
>  }
>
>  /*
> @@ -561,7 +600,7 @@ static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
>         __u32 data;
>         int ret;
>
> -       hid_concatenate_usage_page(parser);
> +       hid_concatenate_last_usage_page(parser);
>
>         data = item_udata(item);
>
> @@ -772,7 +811,7 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
>         __u32 data;
>         int i;
>
> -       hid_concatenate_usage_page(parser);
> +       hid_concatenate_last_usage_page(parser);
>
>         data = item_udata(item);
>
> --
> 2.17.1
>