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<a href="https://gitlab.rtems.org/Chloe">Yang Zhang</a> created a merge request: <a href="https://gitlab.rtems.org/rtems/rtos/rtems/-/merge_requests/1306">!1306</a>
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Project:Branches: Chloe/rtems:fix-gic-ppi-irq-mapping to rtems/rtos/rtems:main
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Author: Yang Zhang
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Assignees:
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Reviewers:
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<h2 id="user-content-summary" dir="auto" style="margin-top: 0; margin-bottom: 10px;" align="initial">Summary<a href="#summary" aria-label="Link to heading 'Summary'" data-heading-content="Summary" class="anchor" style="margin-top: 0;"></a>
</h2>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The ARM GIC device tree binding defines three cells per interrupt entry:</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">cell[0]: interrupt type (0 = SPI, 1 = PPI)</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">cell[1]: interrupt number (relative to the type base)</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">cell[2]: trigger flags (no effect on the INTID calculation)</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial"> </p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The GIC hardware INTID layout is:</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">0-15: SGI</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">16-31: PPI</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">32+: SPI</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Therefore the correct absolute hardware INTID is:</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">SPI (type 0): irq_number + 32</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">PPI (type 1): irq_number + 16</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial"> </p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The previous code used a hard-coded offset of 32 for all interrupts in</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">both imx_get_irq_of_node() and bsp_fdt_map_intr(), ignoring the</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">interrupt type entirely.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial"> </p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">The ARM generic timer (used in arm_generic_timer_get_config()) is a PPI</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">interrupt. Since its correct offset is 16 rather than 32, the previous</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">code compensated with a manual "- 16" adjustment at the call site,</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">accompanied by a FIXME comment.</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial"> </p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">Fix this by reading cell[0] in both imx_get_irq_of_node() and</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">bsp_fdt_map_intr() and selecting the correct offset based on the</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">interrupt type, as specified by the ARM GIC device tree binding and</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">implemented by the Linux GIC driver. Remove the unnecessary</p>
<p dir="auto" style="color: #3a383f; margin: 0 0 1rem;" align="initial">adjustment and FIXME comment.</p>
<h2 id="user-content-generative-ai" dir="auto" style="margin-top: 20px; margin-bottom: 10px;" align="initial">Generative AI<a href="#generative-ai" aria-label="Link to heading 'Generative AI'" data-heading-content="Generative AI" class="anchor" style="margin-top: 0;"></a>
</h2>
<p dir="auto" style="color: #3a383f; margin: 0;" align="initial">None</p>
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