Re: [PATCH v2 3/4] firmware: qcom: scm: Add minidump SRAM support

[Mukesh Ojha]

On Thu, May 21, 2026 at 12:21:03PM +0200, Konrad Dybcio wrote:
> On 5/19/26 7:14 PM, Mukesh Ojha wrote:
> > On most Qualcomm SoCs where minidump is supported, a word in always-on
> > SRAM is shared between the kernel and boot firmware. Before DDR is
> > initialised on the warm reset following a crash, firmware reads this
> > word to decide if minidump is enabled and collect a minidump and where
> > to deliver it (USB upload to a host, or save to local storage).
> > 
> > The SRAM region is described by a 'sram' phandle on the SCM DT node.
> > If the property is absent the feature is silently disabled, keeping
> > existing SoCs unaffected.
> > 
> > Expose a 'minidump_dest' module parameter (default: usb) so the user can
> > select the destination. Only the string names "usb" or "storage" are
> > accepted; an invalid value is rejected with -EINVAL. Changing the
> > destination while minidump mode is already active updates SRAM immediately.
> > 
> > Signed-off-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>
> > ---
> 
> [...]
> 
> > +static int qcom_scm_map_minidump_sram(struct device *dev, void __iomem **out)
> > +{
> > +	struct device_node *np = dev->of_node;
> > +	struct device_node *sram_np;
> > +	struct resource res;
> > +	int ret;
> > +
> > +	if (!of_property_present(np, "sram"))
> > +		return 0;
> 
> I think of_parse_phandle() calls this indirectly already
>

Right, will remove and turn below return statement to return 0.

> > +
> > +	sram_np = of_parse_phandle(np, "sram", 0);
> > +	if (!sram_np)
> > +		return -EINVAL;
> > +
> > +	ret = of_address_to_resource(sram_np, 0, &res);
> > +	of_node_put(sram_np);
> > +	if (ret)
> > +		return ret;
> > +
> > +	if (resource_size(&res) < sizeof(u32)) {
> > +		dev_err(dev, "minidump SRAM region too small\n");
> > +		return -EINVAL;
> 
> I don't know if this is possible in practice
> 

Right, will remove it.


> Konrad

-- 
-Mukesh Ojha