Re: [PATCH V1 3/4] soc: qcom: boot_stat: Add Driver Support for Boot Stats

[Souradeep Chowdhury]

On 3/21/2023 11:07 PM, Krzysztof Kozlowski wrote:
> On 21/03/2023 14:51, Souradeep Chowdhury wrote:
> > All of Qualcomm's proprietary Android boot-loaders capture boot time
> > stats, like the time when the bootloader started execution and at what
> > point the bootloader handed over control to the kernel etc. in the IMEM
> > region. This information is captured in a specific format by this driver
> > by mapping a structure to the IMEM memory region and then accessing the
> > members of the structure to print the information. This information is
> > useful in verifying if the existing boot KPIs have regre
>
>
> > +/**
> > + *  struct boot_stats - timestamp information related to boot stats
> > + *  @bootloader_start:	Time for the starting point of the abl bootloader
> > + *  @bootloader_end:	Time when the kernel starts loading from abl bootloader
> > + */
> > +struct boot_stats {
> > +	u32 bootloader_start;
> > +	u32 bootloader_end;
> > +} __packed;
> > +
> > +static struct boot_stats __iomem *boot_stats;
> > +static void __iomem *mpm_counter_base;
> > +static u32 mpm_counter_freq;
>
> No file-scope variables. Does not scale, not easy for review and
> maintenance. Avoid such code.

Ack
> > +
> > +static int mpm_parse_dt(void)
> > +{
> > +	struct device_node *np_imem, *np_mpm2;
> > +
> > +	np_imem = of_find_compatible_node(NULL, NULL,
> > +					  "qcom,imem-boot_stats");
> > +	if (!np_imem) {
> > +		pr_err("can't find qcom,imem node\n");
>
> So you are printing errors everywhere, on every soc and with compile
> test on every platform there is in the world... sorry, it does not work
> like that.

Ack
> > +		return -ENODEV;
> > +	}
> > +	boot_stats = of_iomap(np_imem, 0);
> > +	if (!boot_stats) {
> > +		pr_err("boot_stats: Can't map imem\n");
> > +		goto err1;
> > +	}
>
>
> > +
> > +static void __exit boot_stats_exit(void)
> > +{
> > +}
> > +module_exit(boot_stats_exit)
>
>
> I don't think this is some special code which deserves init calls. Make
> it module_platform_driver().

Since this just reads some values from the Imem region and prints it to 
the user and doesn't have a specific device associated with it, a 
generic module code is written for it and not a module_platform_driver().

> Best regards,
> Krzysztof