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Message-ID: <20230829143851.00006467@Huawei.com>
Date: Tue, 29 Aug 2023 14:38:51 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Terry Bowman <terry.bowman@....com>
CC: <alison.schofield@...el.com>, <vishal.l.verma@...el.com>,
<ira.weiny@...el.com>, <bwidawsk@...nel.org>,
<dan.j.williams@...el.com>, <dave.jiang@...el.com>,
<linux-cxl@...r.kernel.org>, <rrichter@....com>,
<linux-kernel@...r.kernel.org>, <bhelgaas@...gle.com>
Subject: Re: [PATCH v9 01/15] cxl/port: Pre-initialize component register
mappings
On Fri, 25 Aug 2023 18:31:57 -0500
Terry Bowman <terry.bowman@....com> wrote:
> From: Robert Richter <rrichter@....com>
Hi Robert, Terry,
>
> The component registers of a component may not exist or are not
> needed.
How do we now it's not needed in this function?
Perhaps "may not exist." is the bit that matters in this sentence.
> The setup may fail for that reason. In some cases the
> initialization should continue anyway. Thus, always initialize struct
> cxl_register_map with valid values. In case of errors, zero it, set a
> value for @dev and make @resource a the valid value using
make @resource CXL_RESOURCE_NONE.
(not "a the")
> CXL_RESOURCE_NONE.
It might be worth making it clear that this will (I think) only matter
for future usecases and isn't a fix for how this function is used today.
>
> Signed-off-by: Robert Richter <rrichter@....com>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
Otherwise seems sensible to me with one comment below.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
> drivers/cxl/core/port.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 724be8448eb4..2d22e7a5629b 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -693,16 +693,17 @@ static struct cxl_port *cxl_port_alloc(struct device *uport_dev,
> static int cxl_setup_comp_regs(struct device *dev, struct cxl_register_map *map,
> resource_size_t component_reg_phys)
> {
> - if (component_reg_phys == CXL_RESOURCE_NONE)
> - return 0;
> -
> *map = (struct cxl_register_map) {
> .dev = dev,
> - .reg_type = CXL_REGLOC_RBI_COMPONENT,
Could set this explicitly to CXL_REGLOC_RBI_EMPTY
which is what happens anyway, but it isn't obvious that
0 maps to something that indicates this doesn't exist.
> .resource = component_reg_phys,
> - .max_size = CXL_COMPONENT_REG_BLOCK_SIZE,
> };
>
> + if (component_reg_phys == CXL_RESOURCE_NONE)
> + return 0;
> +
> + map->reg_type = CXL_REGLOC_RBI_COMPONENT;
> + map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;
> +
> return cxl_setup_regs(map);
> }
>
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