linux-kernel - Re: [PATCH] firmware: arm_scmi: Add missing Rx size re-initialisation

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Message-ID: <CAN5uoS_GHXv-RHJACJMJqN_xRSSWuv=mTPW_aHZv5U6PjK16xg@mail.gmail.com>
Date:   Tue, 13 Oct 2020 11:58:09 +0200
From:   Etienne Carriere <etienne.carriere@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-kernel@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        Cristian Marussi <cristian.marussi@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Souvik Chakravarty <Souvik.Chakravarty@....com>
Subject: Re: [PATCH] firmware: arm_scmi: Add missing Rx size re-initialisation

On Mon, 12 Oct 2020 at 16:17, Sudeep Holla <sudeep.holla@....com> wrote:
>
> Few commands provide the list of description partially and require
> to be called consecutively until all the descriptors are fetched
> completely. In such cases, we don't release the buffers and reuse
> them for consecutive transmits.
>
> However, currently we don't reset the Rx size which will be set as
> per the response for the last transmit. This may result in incorrect
> response size being interpretted as the firmware may repond with size
> greater than the one set but we read only upto the size set by previous
> response.
>
> Let us reset the receive buffer size to max possible in such cases as
> we don't know the exact size of the response.
>
> Fixes: b6f20ff8bd94 ("firmware: arm_scmi: add common infrastructure and support for base protocol")
> Reported-by: Etienne Carriere <etienne.carriere@...aro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/arm_scmi/base.c    | 2 ++
>  drivers/firmware/arm_scmi/clock.c   | 2 ++
>  drivers/firmware/arm_scmi/common.h  | 8 ++++++++
>  drivers/firmware/arm_scmi/perf.c    | 2 ++
>  drivers/firmware/arm_scmi/sensors.c | 2 ++
>  5 files changed, 16 insertions(+)
>
> Hi Etienne,
>
> I reworked this in a different way and hence dropped your authorship and added
> reported by. If you prefer I can attribute you as author. I want to push
> 2,4,5/5 as fixes and hence the rush.

Hi Sudeep,

Tags are fine like that.
As for the content, it looks good to me.
When trying to apply this, I failed, but I guess I'm not testing over
the same kernel tree/branch as you.
All in one, I am really fine with this change, I think it does the job

Regards,
Etienne

>
> Regards,
> Sudeep
>
> diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
> index 9853bd3c4d45..017e5d8bd869 100644
> --- a/drivers/firmware/arm_scmi/base.c
> +++ b/drivers/firmware/arm_scmi/base.c
> @@ -197,6 +197,8 @@ static int scmi_base_implementation_list_get(const struct scmi_handle *handle,
>                         protocols_imp[tot_num_ret + loop] = *(list + loop);
>
>                 tot_num_ret += loop_num_ret;
> +
> +               scmi_reset_rx_to_maxsz(handle, t);
>         } while (loop_num_ret);
>
>         scmi_xfer_put(handle, t);
> diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
> index c1cfe3ee3d55..4645677d86f1 100644
> --- a/drivers/firmware/arm_scmi/clock.c
> +++ b/drivers/firmware/arm_scmi/clock.c
> @@ -192,6 +192,8 @@ scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
>                 }
>
>                 tot_rate_cnt += num_returned;
> +
> +               scmi_reset_rx_to_maxsz(handle, t);
>                 /*
>                  * check for both returned and remaining to avoid infinite
>                  * loop due to buggy firmware
> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> index 37fb583f1bf5..a3f1bc44b1de 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -245,6 +245,14 @@ extern const struct scmi_desc scmi_mailbox_desc;
>  extern const struct scmi_desc scmi_smc_desc;
>  #endif
>
> +static inline void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
> +                                         struct scmi_xfer *xfer)
> +{
> +       struct scmi_info *info = handle_to_scmi_info(handle);
> +
> +       xfer->rx.len = info->desc->max_msg_size;
> +}
> +
>  void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr);
>  void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id);
>
> diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
> index ed475b40bd08..82fb3babff72 100644
> --- a/drivers/firmware/arm_scmi/perf.c
> +++ b/drivers/firmware/arm_scmi/perf.c
> @@ -304,6 +304,8 @@ scmi_perf_describe_levels_get(const struct scmi_handle *handle, u32 domain,
>                 }
>
>                 tot_opp_cnt += num_returned;
> +
> +               scmi_reset_rx_to_maxsz(handle, t);
>                 /*
>                  * check for both returned and remaining to avoid infinite
>                  * loop due to buggy firmware
> diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
> index 9703cf6356a0..b4232d611033 100644
> --- a/drivers/firmware/arm_scmi/sensors.c
> +++ b/drivers/firmware/arm_scmi/sensors.c
> @@ -166,6 +166,8 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
>                 }
>
>                 desc_index += num_returned;
> +
> +               scmi_reset_rx_to_maxsz(handle, t);
>                 /*
>                  * check for both returned and remaining to avoid infinite
>                  * loop due to buggy firmware
> --
> 2.17.1
>