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Mon, 30 Jun 2025 05:54:12 -0700 (PDT) Message-ID: <423f101a-0826-4b7c-ace7-f5e7f4790c4c@linaro.org> Date: Mon, 30 Jun 2025 13:54:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/6] spi: spi-fsl-dspi: Store status directly in cur_msg->status To: Vladimir Oltean Cc: Vladimir Oltean , Mark Brown , Arnd Bergmann , Larisa Grigore , Frank Li , Christoph Hellwig , linux-spi@vger.kernel.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org References: <20250627-james-nxp-spi-dma-v4-0-178dba20c120@linaro.org> <20250627-james-nxp-spi-dma-v4-2-178dba20c120@linaro.org> <20250627213041.vp6yfcgf4xysdklf@skbuf> Content-Language: en-US From: James Clark In-Reply-To: <20250627213041.vp6yfcgf4xysdklf@skbuf> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 27/06/2025 10:30 pm, Vladimir Oltean wrote: > On Fri, Jun 27, 2025 at 11:21:38AM +0100, James Clark wrote: >> This will allow us to return a status from the interrupt handler in a >> later commit and avoids copying it at the end of >> dspi_transfer_one_message(). For consistency make polling and DMA modes >> use the same mechanism. >> >> Refactor dspi_rxtx() and dspi_poll() to not return -EINPROGRESS because >> this isn't actually a status that was ever returned to the core layer >> but some internal state. Wherever that was used we can look at dspi->len >> instead. >> >> No functional changes intended. >> >> Signed-off-by: James Clark >> --- > > This commit doesn't work, please do not merge this patch. > > You are changing the logic in DMA mode, interrupt-based FIFO and PIO all > in one go, in a commit whose title and primary purpose is unrelated to > that. Just a mention of the type "while at it, also do that". And in > that process, that bundled refactoring introduces a subtle, but severe bug. > > No, that is discouraged. Make one patch per logical change, where only > one thing is happening and which is obviously correct. It helps you and > it helps the reviewer. > > Please find attached a set of 3 patches that represent a broken down and > corrected variant of this one. First 2 should be squashed together in > your next submission, they are just to illustrate the bug that you've > introduced (which can be reproduced on any SoC in XSPI mode). > Thanks for the debugging, yes it looks like the patches could be broken down a bit. Just for clarity, is this bug affecting host+polling mode? I can see the logic bug in dspi_poll() which I must have tested less thoroughly, but I can't actually see any difference in dspi_interrupt(). WRT the patches attached, we could remove dspi_rxtx(). It's only encapsulating two function calls, and the return half way through is something that is for the outer loop in the caller anyway. Open open coding the dspi_fifo_read() and dspi_fifo_write() ends up being clearer IMO. > The panic message is slightly confusing and does not directly point to > the issue, I'm attaching it just for the sake of having a future reference. > The panic is a bit confusing, I didn't expect to see dspi_interrupt() if it only affects polling mode. Do you have a reproducer? I wasn't able to reproduce it in interrupt mode. > [ 4.154185] DSA: tree 0 setup > [ 4.157380] sja1105 spi2.0: Probed switch chip: SJA1105S > [ 4.173894] sja1105 spi2.0: configuring for fixed/sgmii link mode > [ 4.232527] sja1105 spi2.0: Link is Up - 1Gbps/Full - flow control off > [ 4.312798] sja1105 spi2.0 sw0p0 (uninitialized): PHY [0000:00:00.3:07] driver [RTL8211F Gigabit Ethernet] (irq=POLL) > [ 4.443689] sja1105 spi2.0 sw0p1 (uninitialized): PHY [0000:00:00.3:00] driver [Microsemi GE VSC8502 SyncE] (irq=POLL) > [ 4.575718] sja1105 spi2.0 sw0p2 (uninitialized): PHY [0000:00:00.3:01] driver [Microsemi GE VSC8502 SyncE] (irq=POLL) > [ 4.588012] Unable to handle kernel paging request at virtual address ffff8000801ac000 > [ 4.595960] Mem abort info: > [ 4.598757] ESR = 0x0000000096000007 > [ 4.602515] EC = 0x25: DABT (current EL), IL = 32 bits > [ 4.607843] SET = 0, FnV = 0 > [ 4.610902] EA = 0, S1PTW = 0 > [ 4.614048] FSC = 0x07: level 3 translation fault > [ 4.618939] Data abort info: > [ 4.621822] ISV = 0, ISS = 0x00000007, ISS2 = 0x00000000 > [ 4.627323] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 > [ 4.632388] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 > [ 4.637714] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000082b7a000 > [ 4.644437] [ffff8000801ac000] pgd=0000000000000000, p4d=1000002080020403, pud=1000002080021403, pmd=1000002080022403, pte=0000000000000000 > [ 4.657016] Internal error: Oops: 0000000096000007 [#1] SMP > [ 4.662693] Modules linked in: > [ 4.665756] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.16.0-rc3+ #30 PREEMPT > [ 4.673615] Hardware name: random LS1028A board > [ 4.679116] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 4.686103] pc : dspi_8on32_host_to_dev+0x8/0x24 > [ 4.690742] lr : dspi_fifo_write+0x178/0x1cc > [ 4.695025] sp : ffff800080003eb0 > [ 4.698346] x29: ffff800080003ec0 x28: ffffc25414698b00 x27: ffffc2541464c170 > [ 4.705512] x26: 0000000000000001 x25: ffffc25414b06000 x24: 0000000111705fd3 > [ 4.712677] x23: ffffc25414257bae x22: ffff8000801ab5e8 x21: 00000000fffffd98 > [ 4.719842] x20: 0000000000000000 x19: ffff00200039a480 x18: 0000000000000006 > [ 4.727007] x17: ffff3dcc6b076000 x16: ffff800080000000 x15: 0000000078b30c40 > [ 4.734171] x14: 0000000000000000 x13: 0000000000000048 x12: 0000000000000128 > [ 4.741335] x11: 0000000000000001 x10: 0000000000000000 x9 : 0000000100010001 > [ 4.748500] x8 : ffff8000801ac000 x7 : 0000000000000000 x6 : 0000000000000000 > [ 4.755664] x5 : 0000000000000000 x4 : ffffc25411a308d0 x3 : 0000000000000000 > [ 4.762828] x2 : 0000000000000000 x1 : ffff800080003eb4 x0 : ffff00200039a480 > [ 4.769992] Call trace: > [ 4.772441] dspi_8on32_host_to_dev+0x8/0x24 (P) > [ 4.777074] dspi_interrupt+0x6c/0xf0 > [ 4.780747] __handle_irq_event_percpu+0x8c/0x160 > [ 4.785470] handle_irq_event+0x48/0xa0 > [ 4.789319] handle_fasteoi_irq+0xf4/0x208 > [ 4.793428] generic_handle_domain_irq+0x40/0x64 > [ 4.798060] gic_handle_irq+0x4c/0x110 > [ 4.801820] call_on_irq_stack+0x24/0x30 > [ 4.805757] el1_interrupt+0x74/0xc0 > [ 4.809346] el1h_64_irq_handler+0x18/0x24 > [ 4.813457] el1h_64_irq+0x6c/0x70 > [ 4.816867] arch_local_irq_enable+0x8/0xc (P) > [ 4.821330] cpuidle_enter+0x38/0x50 > [ 4.824914] do_idle+0x1c4/0x250 > [ 4.828152] cpu_startup_entry+0x34/0x38 > [ 4.832087] kernel_init+0x0/0x1a0 > [ 4.835500] start_kernel+0x2ec/0x398 > [ 4.839175] __primary_switched+0x88/0x90 > [ 4.843200] Code: f9003008 d65f03c0 d503245f f9402c08 (b9400108) > [ 4.849313] ---[ end trace 0000000000000000 ]--- > [ 4.853943] Kernel panic - not syncing: Oops: Fatal exception in interrupt > [ 4.860840] SMP: stopping secondary CPUs > [ 4.864788] Kernel Offset: 0x425391a00000 from 0xffff800080000000 > [ 4.870900] PHYS_OFFSET: 0xfff1000080000000 > [ 4.875093] CPU features: 0x1000,000804b0,02000801,0400421b > [ 4.880683] Memory Limit: none > [ 4.883750] ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]--- > > I still intend to do more testing, so please don't send the next version > just yet. Tracking down this issue took a bit more than I was planning. We could also revert to the original idea of adding the status int to struct fsl_dspi. Much simpler and nothing needs to be changed except reading it out in interrupt mode.