From: Manivannan Sadhasivam <mani@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: "Manivannan Sadhasivam" <mani@kernel.org>,
"Damien Le Moal" <damien.lemoal@opensource.wdc.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
linux-pci@vger.kernel.org,
"Rick Wertenbroek" <rick.wertenbroek@gmail.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v2 09/16] PCI: epf-test: Improve handling of command and status registers
Date: Thu, 16 Mar 2023 22:01:33 +0530 [thread overview]
Message-ID: <20230316163133.GA123754@thinkpad> (raw)
In-Reply-To: <d2f42b13-3d1e-4fb9-8b03-b32b7a9845a9@app.fastmail.com>
On Thu, Mar 16, 2023 at 04:25:58PM +0100, Arnd Bergmann wrote:
> On Wed, Mar 15, 2023, at 16:51, Manivannan Sadhasivam wrote:
> > On Wed, Mar 08, 2023 at 06:03:06PM +0900, Damien Le Moal wrote:
> >> + /*
> >> + * Set the status before raising the IRQ to ensure that the host sees
> >> + * the updated value when it gets the IRQ.
> >> + */
> >> + WRITE_ONCE(reg->status, status);
> >
> > For MMIO, it is not sufficient to use WRITE_ONCE() and expect that the write
> > has reached the memory (it could be stored in a write buffer). If you really
> > care about synchronization, then you should do a read back of the variable.
>
> This is not MMIO, this is the local access to a variable that is accessed
> through MMIO from the remote host. Reading it back would not change anything
> here as far as I can tell,
>
Ah, sorry I got confused this with my EPF driver... Yeah for a variable
WRITE_ONCE is sufficient.
Thanks,
Mani
> Arnd
--
மணிவண்ணன் சதாசிவம்
next prev parent reply other threads:[~2023-03-16 16:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-08 9:02 [PATCH v2 00/16] PCI endpoint fixes and improvements Damien Le Moal
2023-03-08 9:02 ` [PATCH v2 01/16] PCI: endpoint: Automatically create a function specific attributes group Damien Le Moal
2023-03-15 14:27 ` Manivannan Sadhasivam
2023-03-08 9:02 ` [PATCH v2 02/16] PCI: endpoint: Move pci_epf_type_add_cfs() code Damien Le Moal
2023-03-15 15:01 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 03/16] PCI: epf-test: Fix DMA transfer completion initialization Damien Le Moal
2023-03-15 15:03 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 04/16] PCI: epf-test: Fix DMA transfer completion detection Damien Le Moal
2023-03-15 15:20 ` Manivannan Sadhasivam
2023-03-15 23:46 ` Damien Le Moal
2023-03-08 9:03 ` [PATCH v2 05/16] PCI: epf-test: Use dmaengine_submit() to initiate DMA transfer Damien Le Moal
2023-03-15 15:21 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 06/16] PCI: epf-test: Simplify read/write/copy test functions Damien Le Moal
2023-03-15 15:24 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 07/16] PCI: epf-test: Simply pci_epf_test_raise_irq() Damien Le Moal
2023-03-15 15:27 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 08/16] PCI: epf-test: Simplify IRQ test commands execution Damien Le Moal
2023-03-15 15:37 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 09/16] PCI: epf-test: Improve handling of command and status registers Damien Le Moal
2023-03-15 15:51 ` Manivannan Sadhasivam
2023-03-15 23:49 ` Damien Le Moal
2023-03-16 15:25 ` Arnd Bergmann
2023-03-16 16:31 ` Manivannan Sadhasivam [this message]
2023-03-16 16:32 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 10/16] PCI: epf-test: Cleanup pci_epf_test_cmd_handler() Damien Le Moal
2023-03-15 15:52 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 11/16] PCI: epf-test: Simplify dma support checks Damien Le Moal
2023-03-15 15:57 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 12/16] PCI: epf-test: Simplify transfers result print Damien Le Moal
2023-03-08 9:03 ` [PATCH v2 13/16] misc: pci_endpoint_test: Free IRQs before removing the device Damien Le Moal
2023-03-08 9:03 ` [PATCH v2 14/16] misc: pci_endpoint_test: Re-init completion for every test Damien Le Moal
2023-03-15 15:55 ` Manivannan Sadhasivam
2023-03-08 9:03 ` [PATCH v2 15/16] misc: pci_endpoint_test: Do not write status in IRQ handler Damien Le Moal
2023-03-08 9:03 ` [PATCH v2 16/16] misc: pci_endpoint_test: Simplify pci_endpoint_test_msi_irq() Damien Le Moal
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