On Sun, 29 Oct 2023 at 21:46, Sui Jingfeng <suijingfeng@xxxxxxxxxxx> wrote:
>
> Due to the fact that the same display IP core has been integrated into
> different platform, there is a need to differentiate them on the runtime.
> The DC in LS7A1000/LS2K1000 has the PCI vendor & device ID of 0x0014:0x7A06
> The DC in LS7A2000/LS2K2000 has the PCI vendor & device ID of 0x0014:0x7A36
>
> Because the output ports and host platform of the DC IP varies, without a
> revision information we can't achieve fine-grained controls. The canonical
> approach to do such a thing is to read reversion register from the PCIe
> device. But LS2K1000 SoC was taped out at 2017, it is rather old. Our BIOS
> engineer don't assign a different revision ID to it, probably because of
> ignorance.
>
> LS2K2000 SoC was newly taped on 2023, we strictly force the BIOS engineer
> assign a different revision ID(0x10) to it. But the problem is that it is
> too casual, there is no formal convention or public documented rule
> established. For Loongson LS2K series SoC, the display controller IP is
> taped togather with the CPU core. For Loongson LS7A series bridge chips,
> the display controller IP is taped togather with the bridge chips itself.
> Consider the fact the all Loongson CPU has a unique PRID, this patch choose
> to infer DC reversion from CPU's PRID value.
>
> - LS3A4000/LS3A5000 has 0xC0 as its processor ID.
> - LS2K2000 has 0xB0 as its processor ID.
> - LS2K2000LA has 0xA0 as its processor ID.
>
> The provided approach has no dependency on DT or ACPI, thus is preferfed.
> Besides, this approach can be used to acquire more addtional HW features.
> So the provided method has the potential to bring more benifits.
>
> Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/loongson/lsdc_drv.h | 2 ++
> drivers/gpu/drm/loongson/lsdc_probe.c | 35 +++++++++++++++++++++++++++
> drivers/gpu/drm/loongson/lsdc_probe.h | 2 ++
> 3 files changed, 39 insertions(+)
>
> diff --git a/drivers/gpu/drm/loongson/lsdc_drv.h b/drivers/gpu/drm/loongson/lsdc_drv.h
> index 46ba9b88a30d..e1f4a2db2a0a 100644
> --- a/drivers/gpu/drm/loongson/lsdc_drv.h
> +++ b/drivers/gpu/drm/loongson/lsdc_drv.h
> @@ -42,6 +42,8 @@
> enum loongson_chip_id {
> CHIP_LS7A1000 = 0,
> CHIP_LS7A2000 = 1,
> + CHIP_LS2K1000 = 2,
> + CHIP_LS2K2000 = 3,
> CHIP_LS_LAST,
> };
>
> diff --git a/drivers/gpu/drm/loongson/lsdc_probe.c b/drivers/gpu/drm/loongson/lsdc_probe.c
> index 48ba69bb8a98..f49b642d8f65 100644
> --- a/drivers/gpu/drm/loongson/lsdc_probe.c
> +++ b/drivers/gpu/drm/loongson/lsdc_probe.c
> @@ -54,3 +54,38 @@ unsigned int loongson_cpu_get_prid(u8 *imp, u8 *rev)
>
> return prid;
> }
> +
> +enum loongson_chip_id loongson_chip_id_fixup(enum loongson_chip_id chip_id)
> +{
> + u8 impl;
> +
> + if (loongson_cpu_get_prid(&impl, NULL)) {
> + /*
> + * LS2K2000 only has the LoongArch edition.
> + */
> + if (chip_id == CHIP_LS7A2000) {
> + if (impl == LOONGARCH_CPU_IMP_LS2K2000)
> + return CHIP_LS2K2000;
> + }
> +
> + /*
> + * LS2K1000 has the LoongArch edition(with two LA264 CPU core)
> + * and the Mips edition(with two mips64r2 CPU core), Only the
> + * instruction set of the CPU are changed, the peripheral
> + * devices are basically same.
> + */
> + if (chip_id == CHIP_LS7A1000) {
> +#if defined(__loongarch__)
> + if (impl == LOONGARCH_CPU_IMP_LS2K1000)
> + return CHIP_LS2K1000;
> +#endif
> +
> +#if defined(__mips__)
> + if (impl == LOONGSON_CPU_MIPS_IMP_LS2K)
> + return CHIP_LS2K1000;
> +#endif
Can you drop the ifdefs here? The code blocks do not seem to conflict
with each other.
> + }
> + }
> +
> + return chip_id;
> +}
> diff --git a/drivers/gpu/drm/loongson/lsdc_probe.h b/drivers/gpu/drm/loongson/lsdc_probe.h
> index 8bb6de2e3c64..8c630c5c90ce 100644
> --- a/drivers/gpu/drm/loongson/lsdc_probe.h
> +++ b/drivers/gpu/drm/loongson/lsdc_probe.h
> @@ -9,4 +9,6 @@
> /* Helpers for chip detection */
> unsigned int loongson_cpu_get_prid(u8 *impl, u8 *rev);
>
> +enum loongson_chip_id loongson_chip_id_fixup(enum loongson_chip_id chip_id);
> +
> #endif
> --
> 2.34.1
>
--
With best wishes
Dmitry
