From a195c7ccfb7a21b8118139835e25936ec8722596 Mon Sep 17 00:00:00 2001 From: Jason-JH Lin Date: Thu, 23 Oct 2025 01:16:30 +0800 Subject: mailbox: mtk-cmdq: Refine DMA address handling for the command buffer GCE can only fetch the command buffer address from a 32-bit register. Some SoCs support a 35-bit command buffer address for GCE, which requires a right shift of 3 bits before setting the address into the 32-bit register. A comment has been added to the header of cmdq_get_shift_pa() to explain this requirement. To prevent the GCE command buffer address from being DMA mapped beyond its supported bit range, the DMA bit mask for the device is set during initialization. Additionally, to ensure the correct shift is applied when setting or reading the register that stores the GCE command buffer address, new APIs, cmdq_convert_gce_addr() and cmdq_revert_gce_addr(), have been introduced for consistent operations on this register. The variable type for the command buffer address has been standardized to dma_addr_t to prevent handling issues caused by type mismatches. Fixes: 0858fde496f8 ("mailbox: cmdq: variablize address shift in platform") Signed-off-by: Jason-JH Lin Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Jassi Brar --- include/linux/mailbox/mtk-cmdq-mailbox.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux') diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h index 4c1a91b07de3..e1555e06e7e5 100644 --- a/include/linux/mailbox/mtk-cmdq-mailbox.h +++ b/include/linux/mailbox/mtk-cmdq-mailbox.h @@ -77,6 +77,16 @@ struct cmdq_pkt { size_t buf_size; /* real buffer size */ }; +/** + * cmdq_get_shift_pa() - get the shift bits of physical address + * @chan: mailbox channel + * + * GCE can only fetch the command buffer address from a 32-bit register. + * Some SOCs support more than 32-bit command buffer address for GCE, which + * requires some shift bits to make the address fit into the 32-bit register. + * + * Return: the shift bits of physical address + */ u8 cmdq_get_shift_pa(struct mbox_chan *chan); #endif /* __MTK_CMDQ_MAILBOX_H__ */ -- cgit