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SubjectRe: [PATCH] firmware: imx: Skip return value check for some special SCU firmware APIs
Date
On 25.09.2019 13:09, Anson Huang wrote:
> The SCU firmware does NOT always have return value stored in message
> header's function element even the API has response data, those special
> APIs are defined as void function in SCU firmware, so they should be
> treated as return success always.
>
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> - This patch is based on the patch of https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fpatch%2F11129553%2F&amp;data=02%7C01%7Cleonard.crestez%40nxp.com%7Cc0ced6cd07f04023977008d741a07367%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637050029712216472&amp;sdata=Ccq%2Fb2RJdMqmnL7VXrl8YhOlUwC7bWiUG%2BNmiw4OsSM%3D&amp;reserved=0
> ---
> drivers/firmware/imx/imx-scu.c | 34 ++++++++++++++++++++++++++++++++--
> 1 file changed, 32 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/imx/imx-scu.c b/drivers/firmware/imx/imx-scu.c
> index 869be7a..ced5b12 100644
> --- a/drivers/firmware/imx/imx-scu.c
> +++ b/drivers/firmware/imx/imx-scu.c
> @@ -78,6 +78,11 @@ static int imx_sc_linux_errmap[IMX_SC_ERR_LAST] = {
> -EIO, /* IMX_SC_ERR_FAIL */
> };
>
> +static const struct imx_sc_rpc_msg whitelist[] = {
> + { .svc = IMX_SC_RPC_SVC_MISC, .func = IMX_SC_MISC_FUNC_UNIQUE_ID },
> + { .svc = IMX_SC_RPC_SVC_MISC, .func = IMX_SC_MISC_FUNC_GET_BUTTON_STATUS },
> +};

Until now this low level IPC code didn't treat any svc/func specially
and this seems good.

The imx_scu_call_rpc function already has an have_resp argument and
callers are responsible to fill it. Can't we deal with this by adding an
additional err_ret flag passed by the caller?

We can add wrapper functions to avoid tree-wide changes for all callers.

> +
> static struct imx_sc_ipc *imx_sc_ipc_handle;
>
> static inline int imx_sc_to_linux_errno(int errno)
> @@ -157,11 +162,24 @@ static int imx_scu_ipc_write(struct imx_sc_ipc *sc_ipc, void *msg)
> return 0;
> }
>
> +static bool imx_scu_call_skip_return_value_check(uint8_t svc, uint8_t func)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(whitelist); i++)
> + if (svc == whitelist[i].svc &&
> + func == whitelist[i].func)
> + return true;
> +
> + return false;
> +}
> +
> /*
> * RPC command/response
> */
> int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
> {
> + uint8_t saved_svc, saved_func;
> struct imx_sc_rpc_msg *hdr;
> int ret;
>
> @@ -171,8 +189,11 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
> mutex_lock(&sc_ipc->lock);
> reinit_completion(&sc_ipc->done);
>
> - if (have_resp)
> + if (have_resp) {
> sc_ipc->msg = msg;
> + saved_svc = ((struct imx_sc_rpc_msg *)msg)->svc;
> + saved_func = ((struct imx_sc_rpc_msg *)msg)->func;
> + }
> sc_ipc->count = 0;
> ret = imx_scu_ipc_write(sc_ipc, msg);
> if (ret < 0) {
> @@ -190,7 +211,16 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
>
> /* response status is stored in hdr->func field */
> hdr = msg;
> - ret = hdr->func;
> + /*
> + * Some special SCU firmware APIs do NOT have return value
> + * in hdr->func, but they do have response data, those special
> + * APIs are defined as void function in SCU firmware, so they
> + * should be treated as return success always.
> + */
> + if (!imx_scu_call_skip_return_value_check(saved_svc, saved_func))
> + ret = hdr->func;
> + else
> + ret = 0;
> }
>
> out:
>


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