{"record":{"id":"ffa07232249b35d0","repo":"embassy-rs/embassy","slug":"qspi-data-can-t-be-sent-with-a-data-width-of-none","errorCode":null,"errorMessage":"QSPI data can't be sent with a data width of NONE","messagePattern":"QSPI data can't be sent with a data width of NONE","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"embassy-stm32/src/qspi/mod.rs","lineNumber":384,"sourceCode":"    fn setup_transaction(&mut self, fmode: QspiMode, transaction: &TransferConfig, data_len: Option<usize>) {\n        self.assert_transfer_widths(transaction);\n\n        match (transaction.address, transaction.awidth) {\n            (Some(_), QspiWidth::NONE) => panic!(\"QSPI address can't be sent with an address width of NONE\"),\n            (Some(address), _) => {\n                // u32::bit_width was only stabilized in 1.97\n                let address_bit_width = u32::BITS - address.leading_zeros();\n                if address_bit_width > transaction.address_size.bit_width() as u32 {\n                    panic!(\"QSPI address too large to be represented with the given address size\");\n                }\n            }\n            (None, QspiWidth::NONE) => {}\n            (None, _) => panic!(\"QSPI address is not set, so the address width should be NONE\"),\n        }\n\n        match (data_len, transaction.dwidth) {\n            (Some(0), _) => panic!(\"QSPI data must be at least one byte\"),\n            (Some(_), QspiWidth::NONE) => panic!(\"QSPI data can't be sent with a data width of NONE\"),\n            (Some(_), _) => {}\n            (None, QspiWidth::NONE) => {}\n            (None, _) => panic!(\"QSPI data is empty, so the data width should be NONE\"),\n        }\n\n        T::REGS.fcr().modify(|v| {\n            v.set_csmf(true);\n            v.set_ctcf(true);\n            v.set_ctef(true);\n            v.set_ctof(true);\n        });\n\n        while T::REGS.sr().read().busy() {}\n\n        if let Some(len) = data_len {\n            T::REGS.dlr().write(|v| v.set_dl(len as u32 - 1));\n        }\n","sourceCodeStart":366,"sourceCodeEnd":402,"githubUrl":"https://github.com/embassy-rs/embassy/blob/463a07b963419a1bfe61d5d597c44acb810afb8b/embassy-stm32/src/qspi/mod.rs#L366-L402","documentation":"A data phase was requested (data_len = Some(n>0)) but the data width is QspiWidth::NONE, so no lanes exist to move the data bytes. The library enforces that any data transfer uses an actual width and panics on the mismatch.","triggerScenarios":"Passing a TransferConfig with data_len = Some(len) and dwidth = QspiWidth::NONE into setup_transaction via blocking_read, blocking_write, setup_auto_poll, or setup_command.","commonSituations":"Setting only the data length in a config struct whose dwidth defaulted to NONE; command templates reused for data-bearing operations without updating dwidth.","solutions":["Set dwidth to SING, DUAL, or FOUR whenever data is transferred.","If no data is involved, pass data_len = None together with dwidth = QspiWidth::NONE."],"exampleFix":"// before\nlet t = TransferConfig::new(cmd, QspiWidth::SING, Some(addr), QspiWidth::SING, QspiWidth::NONE);\nt.data_len = Some(4);\nqspi.blocking_read(t);\n// after\nlet t = TransferConfig::new(cmd, QspiWidth::SING, Some(addr), QspiWidth::SING, QspiWidth::SING);\nqspi.blocking_read(t);","handlingStrategy":"validation","validationCode":"fn data_width_ok(len: Option<usize>, w: QspiWidth) -> bool {\n    !(len.is_some() && w == QspiWidth::NONE)\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Set dwidth whenever data_len is set; bundle them in a constructor.","Check existing template configs for default NONE widths before adding data phases."],"tags":["rust","embedded","stm32","qspi","validation"],"backgroundTag":"mutually-exclusive-options","analyzedSha":"463a07b963419a1bfe61d5d597c44acb810afb8b","analyzedAt":"2026-09-10T13:38:26.660Z","contentChangedAt":"2026-09-10T13:38:26.660Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}