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Date: Fri, 26 Jan 2024 09:33:27 -0800
From: Bjorn Andersson <andersson@kernel.org>
To: Tanmay Shah <tanmay.shah@amd.com>
Cc: mathieu.poirier@linaro.org, linux-remoteproc@vger.kernel.org, 
	linux-kernel@vger.kernel.org, Ben Levinsky <ben.levinsky@xilinx.com>
Subject: Re: [PATCH v4 1/2] remoteproc: Make rproc_get_by_phandle() work for
 clusters
Message-ID: <4zq5hvxmvwzk6opqggennih5zq7rsznm2omdrrow3zsy2n6rzi@yqxtogh6jz3u>
References: <20240103221124.3063683-1-tanmay.shah@amd.com>
 <20240103221124.3063683-2-tanmay.shah@amd.com>
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On Wed, Jan 03, 2024 at 02:11:24PM -0800, Tanmay Shah wrote:
> From: Mathieu Poirier <mathieu.poirier@linaro.org>
> 
> Multi-cluster remoteproc designs typically have the following DT
> declaration:
> 
> 	remoteproc_cluster {
> 		compatible = "soc,remoteproc-cluster";
> 
>                 core0: core0 {
> 			compatible = "soc,remoteproc-core"
>                         memory-region;
>                         sram;
>                 };
> 
>                 core1: core1 {
> 			compatible = "soc,remoteproc-core"
>                         memory-region;
>                         sram;
>                 }
>         };

The indention of this snippet looks weird in my client, because it
contains a mixture of tabs and spaces. Please clean that up, and while
at it, '_' is not a valid character in DT node names...

> 
> A driver exists for the cluster rather than the individual cores
> themselves so that operation mode and HW specific configurations
> applicable to the cluster can be made.
> 
> Because the driver exists at the cluster level and not the individual
> core level, function rproc_get_by_phandle() fails to return the
> remoteproc associated with the phandled it is called for.
> 
> This patch enhances rproc_get_by_phandle() by looking for the cluster's
> driver when the driver for the immediate remoteproc's parent is not
> found.
> 
> Reported-by: Ben Levinsky <ben.levinsky@xilinx.com>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

The s-o-b is used to certify the origin of the patch, Mathieu provided
his signature here, then as you handle the patch you need to append your
s-o-b to provide the same certification.

The for appropriate tracking of reality, Mathieu should append his s-o-b
when/if he applies the patch.

TL;DR please add your S-o-b after Mathieu's.


Change itself looks good to me.

Regards,
Bjorn

> ---
>  drivers/remoteproc/remoteproc_core.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 695cce218e8c..0b3b34085e2f 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -33,6 +33,7 @@
>  #include <linux/idr.h>
>  #include <linux/elf.h>
>  #include <linux/crc32.h>
> +#include <linux/of_platform.h>
>  #include <linux/of_reserved_mem.h>
>  #include <linux/virtio_ids.h>
>  #include <linux/virtio_ring.h>
> @@ -2112,6 +2113,7 @@ EXPORT_SYMBOL(rproc_detach);
>  struct rproc *rproc_get_by_phandle(phandle phandle)
>  {
>  	struct rproc *rproc = NULL, *r;
> +	struct device_driver *driver;
>  	struct device_node *np;
>  
>  	np = of_find_node_by_phandle(phandle);
> @@ -2122,7 +2124,26 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
>  	list_for_each_entry_rcu(r, &rproc_list, node) {
>  		if (r->dev.parent && device_match_of_node(r->dev.parent, np)) {
>  			/* prevent underlying implementation from being removed */
> -			if (!try_module_get(r->dev.parent->driver->owner)) {
> +
> +			/*
> +			 * If the remoteproc's parent has a driver, the
> +			 * remoteproc is not part of a cluster and we can use
> +			 * that driver.
> +			 */
> +			driver = r->dev.parent->driver;
> +
> +			/*
> +			 * If the remoteproc's parent does not have a driver,
> +			 * look for the driver associated with the cluster.
> +			 */
> +			if (!driver) {
> +				if (r->dev.parent->parent)
> +					driver = r->dev.parent->parent->driver;
> +				if (!driver)
> +					break;
> +			}
> +
> +			if (!try_module_get(driver->owner)) {
>  				dev_err(&r->dev, "can't get owner\n");
>  				break;
>  			}
> -- 
> 2.25.1
>