linux-kernel - Re: [PATCH 2/2] remoteproc: Remove firmware_loading

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Date:   Fri, 16 Dec 2016 09:26:52 +0100
From:   loic pallardy <loic.pallardy@...com>
To:     Sarangdhar Joshi <spjoshi@...eaurora.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Santosh Shilimkar <ssantosh@...nel.org>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arm-msm@...r.kernel.org>, Dave Gerlach <d-gerlach@...com>,
        Suman Anna <s-anna@...com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Trilok Soni <tsoni@...eaurora.org>
Subject: Re: [PATCH 2/2] remoteproc: Remove firmware_loading_complete



On 12/16/2016 01:03 AM, Sarangdhar Joshi wrote:
> rproc_del() waits on firmware_loading_complete in order to
> make sure rproc_add() completed successfully before calling
> rproc_shutdown().  However since rproc_add() will always be
> called before rproc_del(), we do not need to wait on
> firmware_loading_complete. Drop this completion variable
> altogether.
>
Hi,

firmware_loading_complete is used to synchronize all operations on rproc 
with parallel work launched by request_firmware_nowait.
rproc_add could be done and firmware loading still pending. In that case 
rproc_del mustn't be called before end of the procedure.

If you decide to remove this synchronization you need either to modify 
rproc boot sequence or to replace it by something else.

Regards,
Loic

> Signed-off-by: Sarangdhar Joshi <spjoshi@...eaurora.org>
> ---
>
> Sending this patch again since I had missed usage of
> firmware_loading_complete in drivers/soc/ti/wkup_m3_ipc.c
>
>  drivers/remoteproc/remoteproc_core.c | 12 +-----------
>  include/linux/remoteproc.h           |  2 --
>  2 files changed, 1 insertion(+), 13 deletions(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 953ee29..862fa4e 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -975,17 +975,12 @@ static void rproc_fw_config_virtio(const struct firmware *fw, void *context)
>  		rproc_boot(rproc);
>
>  	release_firmware(fw);
> -	/* allow rproc_del() contexts, if any, to proceed */
> -	complete_all(&rproc->firmware_loading_complete);
>  }
>
>  static int rproc_add_virtio_devices(struct rproc *rproc)
>  {
>  	int ret;
>
> -	/* rproc_del() calls must wait until async loader completes */
> -	init_completion(&rproc->firmware_loading_complete);
> -
>  	/*
>  	 * We must retrieve early virtio configuration info from
>  	 * the firmware (e.g. whether to register a virtio device,
> @@ -997,10 +992,8 @@ static int rproc_add_virtio_devices(struct rproc *rproc)
>  	ret = request_firmware_nowait(THIS_MODULE, FW_ACTION_HOTPLUG,
>  				      rproc->firmware, &rproc->dev, GFP_KERNEL,
>  				      rproc, rproc_fw_config_virtio);
> -	if (ret < 0) {
> +	if (ret < 0)
>  		dev_err(&rproc->dev, "request_firmware_nowait err: %d\n", ret);
> -		complete_all(&rproc->firmware_loading_complete);
> -	}
>
>  	return ret;
>  }
> @@ -1483,9 +1476,6 @@ int rproc_del(struct rproc *rproc)
>  	if (!rproc)
>  		return -EINVAL;
>
> -	/* if rproc is just being registered, wait */
> -	wait_for_completion(&rproc->firmware_loading_complete);
> -
>  	/* if rproc is marked always-on, rproc_add() booted it */
>  	/* TODO: make sure this works with rproc->power > 1 */
>  	if (rproc->auto_boot)
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e2f3a32..19d84a0 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -397,7 +397,6 @@ enum rproc_crash_type {
>   * @num_traces: number of trace buffers
>   * @carveouts: list of physically contiguous memory allocations
>   * @mappings: list of iommu mappings we initiated, needed on shutdown
> - * @firmware_loading_complete: marks e/o asynchronous firmware loading
>   * @bootaddr: address of first instruction to boot rproc with (optional)
>   * @rvdevs: list of remote virtio devices
>   * @subdevs: list of subdevices, to following the running state
> @@ -428,7 +427,6 @@ struct rproc {
>  	int num_traces;
>  	struct list_head carveouts;
>  	struct list_head mappings;
> -	struct completion firmware_loading_complete;
>  	u32 bootaddr;
>  	struct list_head rvdevs;
>  	struct list_head subdevs;
>