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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 11, 2023 at 01:15:14AM +0800, Michael Shavit wrote: > > > > What dead code? Is the deal here that we keep the field, but still > > > > infer the value to write from (cd_table->l1_desc == null) in > > > > arm_smmu_write_strtab_ent?? > > > > > > Keep the field and write it directly when populating the ste (i.e. don't > > > infer anything), but the field moves into 'struct arm_smmu_ctx_desc_cfg'. > > > > Yes - the 'dead code' is that we introduce storage for a field that is > > always a known constant (STRTAB_STE_0_S1FMT_64K_L2). > > I'm not sure we're on the same page here. s1fmt could contain either > `STRTAB_STE_0_S1FMT_64K_L2` or `STRTAB_STE_0_S1FMT_LINEAR`, and this > value will be directly copied in arm_smmu_write_strtab_ent. Ah, I did not check this closely, Will said: > But the computation isn't happening -- the STRTAB_STE_0_S1FMT_64K_L2 > constant is hardcoded here. So the nuanced answer is that computation is happening because today the format of the CD table (linear vs 64k) is encoded in l1_desc: + cd_table->l1_desc ? + STRTAB_STE_0_S1FMT_64K_L2 : + STRTAB_STE_0_S1FMT_LINEAR); So I would suggest that along with adding s1fmt to arm_smmu_ctx_desc_cfg you also go and normalize the usage: @@ -1030,7 +1030,7 @@ static __le64 *arm_smmu_get_cd_ptr(struct arm_smmu_master *master, u32 ssid) struct arm_smmu_device *smmu = master->smmu; struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table; - if (!cd_table->l1_desc) + if (cd_table->s1fmt == STRTAB_STE_0_S1FMT_LINEAR) return cd_table->cdtab + ssid * CTXDESC_CD_DWORDS; Jason _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel