Re: [PATCH v2 4/9] remoteproc: mediatek: Support probing for the 2nd core of dual-core SCP
From: Mathieu Poirier <mathieu.poirier@linaro.org>
Date: 2022-08-29 19:42:58
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chrome-platform, linux-arm-kernel, linux-mediatek, linux-remoteproc, lkml
On Wed, Jun 08, 2022 at 04:35:48PM +0800, Tinghan Shen wrote:
The mtk_scp.c driver only supports the single core SCP and the 1st core of a dual-core SCP. This patch extends it for the 2nd core. MT8195 SCP is a dual-core MCU. Both cores are housed in the same subsys.
s/subsys/subsystem
They have the same viewpoint of registers and memory. Core 1 of the SCP features its own set of core configuration registers, interrupt controller, timers, and DMAs. The rest of the peripherals in this subsystem are shared by core 0 and core 1. As for memory, core 1 has its own cache memory. the SCP SRAM is shared
/the/The
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by core 0 and core 1. Signed-off-by: Tinghan Shen <redacted> --- drivers/remoteproc/mtk_scp.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c index 3510c6d0bbc8..91b4aefde4ac 100644 --- a/drivers/remoteproc/mtk_scp.c +++ b/drivers/remoteproc/mtk_scp.c@@ -23,6 +23,10 @@ #define MAX_CODE_SIZE 0x500000 #define SECTION_NAME_IPI_BUFFER ".ipi_buffer" +#define SCP_CORE_0 0 +#define SCP_CORE_1 1 +#define SCP_CORE_SINGLE 0xF + /** * scp_get() - get a reference to SCP. *@@ -836,6 +840,7 @@ static int scp_probe(struct platform_device *pdev) struct resource *res; const char *fw_name = "scp.img"; int ret, i; + u32 core_id = SCP_CORE_SINGLE; ret = rproc_of_parse_firmware(dev, 0, &fw_name); if (ret < 0 && ret != -EINVAL)@@ -851,8 +856,16 @@ static int scp_probe(struct platform_device *pdev) scp->data = of_device_get_match_data(dev); platform_set_drvdata(pdev, scp); + ret = of_property_read_u32_index(dev->of_node, "mediatek,scp-core", 1, &core_id); + if (ret == 0) + dev_info(dev, "Boot SCP dual core %u\n", core_id);
Why is the DT property "mediatek,scp-core" needed at all? Since the compatible "mediatek,mt8195-scp-dual" has already been defined previously in this patchset, initialising the second core, if present, is a matter of looking at the compatile string.
+ res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "sram"); - scp->sram_base = devm_ioremap_resource(dev, res); + if (core_id == SCP_CORE_1) + scp->sram_base = devm_ioremap(dev, res->start, resource_size(res)); + else + scp->sram_base = devm_ioremap_resource(dev, res); +
This looks very broken... For this to work you would need to have two DT entries with the "mediatek,mt8195-scp-dual" compatible properly, one with "mediatek,scp-core = <&scp_dual1 0>;" and another one with "mediatek,scp-core = <&scp_dual0 1>;". Which is also very broken... Here you have a binding whose first argument is a reference to the core sibling while the second argument is a characteristic of the current core, which is highly confusing. I suggest what when you see the compatible binding "mediatek,mt8195-scp", a single core is initialized. If you see "mediatek,mt8195-scp-dual", both cores are initialized as part of the _same_ probe. If the above analysis is not correct it means I misinterpreted your work and if so, a serious amount of comments is needed _and_ a very detailed example in "mtk,scp.yaml" that leaves no room for interpretation. I will stop reviewing this patchset until you have clarified how this works. Thanks, Mathieu
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if (IS_ERR(scp->sram_base)) return dev_err_probe(dev, PTR_ERR(scp->sram_base), "Failed to parse and map sram memory\n");@@ -873,7 +886,12 @@ static int scp_probe(struct platform_device *pdev) scp->l1tcm_phys = res->start; } - scp->reg_base = devm_platform_ioremap_resource_byname(pdev, "cfg"); + res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg"); + if (core_id == SCP_CORE_1) + scp->reg_base = devm_ioremap(dev, res->start, resource_size(res)); + else + scp->reg_base = devm_ioremap_resource(dev, res); + if (IS_ERR(scp->reg_base)) return dev_err_probe(dev, PTR_ERR(scp->reg_base), "Failed to parse and map cfg memory\n");-- 2.18.0