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[2a02:3100:94b4:ad00:84da:62aa:2ccb:3fc3]) by smtp.googlemail.com with ESMTPSA id a21-20020a170906245500b00a4e6c112a95sm2403324ejb.116.2024.04.02.06.54.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Apr 2024 06:54:16 -0700 (PDT) Message-ID: <38eb4bed-f2e9-4e3e-993b-78da54bf988e@gmail.com> Date: Tue, 2 Apr 2024 15:54:16 +0200 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] PCI: Add and use pcim_iomap_region() To: Philipp Stanner , Bjorn Helgaas Cc: "linux-pci@vger.kernel.org" References: <982b02cb-a095-4131-84a7-24817ac68857@gmail.com> <4cf0d7710a74095a14bedc68ba73612943683db4.camel@redhat.com> <348fa275-3922-4ad1-944e-0b5d1dd3cff5@gmail.com> <7af7182d-0f14-4111-b0c4-b57d2d24edd9@gmail.com> Content-Language: en-US From: Heiner Kallweit Autocrypt: addr=hkallweit1@gmail.com; keydata= xsFNBF/0ZFUBEAC0eZyktSE7ZNO1SFXL6cQ4i4g6Ah3mOUIXSB4pCY5kQ6OLKHh0FlOD5/5/ sY7IoIouzOjyFdFPnz4Bl3927ClT567hUJJ+SNaFEiJ9vadI6vZm2gcY4ExdIevYHWe1msJF MVE4yNwdS+UsPeCF/6CQQTzHc+n7DomE7fjJD5J1hOJjqz2XWe71fTvYXzxCFLwXXbBiqDC9 dNqOe5odPsa4TsWZ09T33g5n2nzTJs4Zw8fCy8rLqix/raVsqr8fw5qM66MVtdmEljFaJ9N8 /W56qGCp+H8Igk/F7CjlbWXiOlKHA25mPTmbVp7VlFsvsmMokr/imQr+0nXtmvYVaKEUwY2g 86IU6RAOuA8E0J5bD/BeyZdMyVEtX1kT404UJZekFytJZrDZetwxM/cAH+1fMx4z751WJmxQ J7mIXSPuDfeJhRDt9sGM6aRVfXbZt+wBogxyXepmnlv9K4A13z9DVLdKLrYUiu9/5QEl6fgI kPaXlAZmJsQfoKbmPqCHVRYj1lpQtDM/2/BO6gHASflWUHzwmBVZbS/XRs64uJO8CB3+V3fa cIivllReueGCMsHh6/8wgPAyopXOWOxbLsZ291fmZqIR0L5Y6b2HvdFN1Xhc+YrQ8TKK+Z4R mJRDh0wNQ8Gm89g92/YkHji4jIWlp2fwzCcx5+lZCQ1XdqAiHQARAQABzSZIZWluZXIgS2Fs bHdlaXQgPGhrYWxsd2VpdDFAZ21haWwuY29tPsLBjgQTAQgAOBYhBGxfqY/yOyXjyjJehXLe ig9U8DoMBQJf9GRVAhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEHLeig9U8DoMSycQ AJbfg8HZEK0ljV4M8nvdaiNixWAufrcZ+SD8zhbxl8GispK4F3Yo+20Y3UoZ7FcIidJWUUJL axAOkpI/70YNhlqAPMsuudlAieeYZKjIv1WV5ucNZ3VJ7dC+dlVqQdAr1iD869FZXvy91KhJ wYulyCf+s4T9YgmLC6jLMBZghKIf1uhSd0NzjyCqYWbk2ZxByZHgunEShOhHPHswu3Am0ftt ePaYIHgZs+Vzwfjs8I7EuW/5/f5G9w1vibXxtGY/GXwgGGHRDjFM7RSprGOv4F5eMGh+NFUJ TU9N96PQYMwXVxnQfRXl8O6ffSVmFx4H9rovxWPKobLmqQL0WKLLVvA/aOHCcMKgfyKRcLah 57vGC50Ga8oT2K1g0AhKGkyJo7lGXkMu5yEs0m9O+btqAB261/E3DRxfI1P/tvDZpLJKtq35 dXsj6sjvhgX7VxXhY1wE54uqLLHY3UZQlmH3QF5t80MS7/KhxB1pO1Cpcmkt9hgyzH8+5org +9wWxGUtJWNP7CppY+qvv3SZtKJMKsxqk5coBGwNkMms56z4qfJm2PUtJQGjA65XWdzQACib 2iaDQoBqGZfXRdPT0tC1H5kUJuOX4ll1hI/HBMEFCcO8++Bl2wcrUsAxLzGvhINVJX2DAQaF aNetToazkCnzubKfBOyiTqFJ0b63c5dqziAgzsFNBF/0ZFUBEADF8UEZmKDl1w/UxvjeyAeX kghYkY3bkK6gcIYXdLRfJw12GbvMioSguvVzASVHG8h7NbNjk1yur6AONfbUpXKSNZ0skV8V fG+ppbaY+zQofsSMoj5gP0amwbwvPzVqZCYJai81VobefTX2MZM2Mg/ThBVtGyzV3NeCpnBa 8AX3s9rrX2XUoCibYotbbxx9afZYUFyflOc7kEpc9uJXIdaxS2Z6MnYLHsyVjiU6tzKCiVOU KJevqvzPXJmy0xaOVf7mhFSNQyJTrZpLa+tvB1DQRS08CqYtIMxRrVtC0t0LFeQGly6bOngr ircurWJiJKbSXVstLHgWYiq3/GmCSx/82ObeLO3PftklpRj8d+kFbrvrqBgjWtMH4WtK5uN5 1WJ71hWJfNchKRlaJ3GWy8KolCAoGsQMovn/ZEXxrGs1ndafu47yXOpuDAozoHTBGvuSXSZo ythk/0EAuz5IkwkhYBT1MGIAvNSn9ivE5aRnBazugy0rTRkVggHvt3/7flFHlGVGpBHxFUwb /a4UjJBPtIwa4tWR8B1Ma36S8Jk456k2n1id7M0LQ+eqstmp6Y+UB+pt9NX6t0Slw1NCdYTW gJezWTVKF7pmTdXszXGxlc9kTrVUz04PqPjnYbv5UWuDd2eyzGjrrFOsJEi8OK2d2j4FfF++ AzOMdW09JVqejQARAQABwsF2BBgBCAAgFiEEbF+pj/I7JePKMl6Fct6KD1TwOgwFAl/0ZFUC GwwACgkQct6KD1TwOgxUfg//eAoYc0Vm4NrxymfcY30UjHVD0LgSvU8kUmXxil3qhFPS7KA+ y7tgcKLHOkZkXMX5MLFcS9+SmrAjSBBV8omKoHNo+kfFx/dUAtz0lot8wNGmWb+NcHeKM1eb nwUMOEa1uDdfZeKef/U/2uHBceY7Gc6zPZPWgXghEyQMTH2UhLgeam8yglyO+A6RXCh+s6ak Wje7Vo1wGK4eYxp6pwMPJXLMsI0ii/2k3YPEJPv+yJf90MbYyQSbkTwZhrsokjQEaIfjrIk3 rQRjTve/J62WIO28IbY/mENuGgWehRlTAbhC4BLTZ5uYS0YMQCR7v9UGMWdNWXFyrOB6PjSu Trn9MsPoUc8qI72mVpxEXQDLlrd2ijEWm7Nrf52YMD7hL6rXXuis7R6zY8WnnBhW0uCfhajx q+KuARXC0sDLztcjaS3ayXonpoCPZep2Bd5xqE4Ln8/COCslP7E92W1uf1EcdXXIrx1acg21 H/0Z53okMykVs3a8tECPHIxnre2UxKdTbCEkjkR4V6JyplTS47oWMw3zyI7zkaadfzVFBxk2 lo/Tny+FX1Azea3Ce7oOnRUEZtWSsUidtIjmL8YUQFZYm+JUIgfRmSpMFq8JP4VH43GXpB/S OCrl+/xujzvoUBFV/cHKjEQYBxo+MaiQa1U54ykM2W4DnHb1UiEf5xDkFd4= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 02.04.2024 15:17, Philipp Stanner wrote: > On Thu, 2024-03-28 at 23:03 +0100, Heiner Kallweit wrote: >> On 28.03.2024 18:35, Heiner Kallweit wrote: >>> On 27.03.2024 14:20, Philipp Stanner wrote: >>>> On Wed, 2024-03-27 at 12:52 +0100, Heiner Kallweit wrote: >>>>> Several drivers use the following sequence for a single BAR: >>>>> rc = pcim_iomap_regions(pdev, BIT(bar), name); >>>>> if (rc) >>>>>         error; >>>>> addr = pcim_iomap_table(pdev)[bar]; >>>>> >>>>> Let's create a simpler (from implementation and usage >>>>> perspective) >>>>> pcim_iomap_region() for this use case. >>>> >>>> I like that idea – in fact, I liked it so much that I wrote that >>>> myself, although it didn't make it vor v6.9 ^^ >>>> >>>> You can look at the code here [1] >>>> >>>> Since my series cleans up the PCI devres API as much as possible, >>>> I'd >>>> argue that prefering it would be better. >>>> >>> Thanks for the hint. I'm not in a hurry, so yes: We should refactor >>> the >>> pcim API, and then add functionality. >>> >>>> But maybe you could do a review, since you're now also familiar >>>> with >>>> the code? >>>> >>> I'm not subscribed to linux-pci, so I missed the cover letter, but >>> had a >>> look at the patches in patchwork. Few remarks: >>> >>> Instead of first adding a lot of new stuff and then cleaning up, >>> I'd >>> propose to start with some cleanups. E.g. patch 7 could come first, >>> this would already allow to remove member mwi from struct >>> pci_devres. >>> >> When looking at the intx members of struct pci_devres: >> Why not simply store the initial state of bit >> PCI_COMMAND_INTX_DISABLE >> in struct pci_dev and restore this bit in do_pci_disable_device()? >> This should allow us to get rid of these members. > > Those members have been there before I touched anything. > Patch #8 removes them entirely, so I'd say that result has been > achieved. > - all the networking people because discussion is solely about PCI core now I think the proposed pcim_intx() is more complex than needed, and I see issues if it's called multiple times. In addition you state that pci_intx() is outdated, but add an API call for the same functionality. Did you see the RFC patches I sent? they could help to reduce the complexity of the pcim refactoring. > Besides, considering the current fragmentation of devres within the PCI > subsystem, I think it's wise to do 100% of devres operations in > devres.c > > P. > >> >>> By the way, in patch 7 it may be a little simpler to have the >>> following >>> sequence: >>> >>> rc = pci_set_mwi() >>> if (rc) >>>         error >>> rc = devm_add_action_or_reset(.., __pcim_clear_mwi, ..); >>> if (rc) >>>         error >>> >>> This would avoid the call to devm_remove_action(). >>> >>> We briefly touched the point whether the proposed new function >>> returns >>> NULL or an ERR_PTR. I find it annoying that often the kernel doc >>> function >>> description doesn't mention whether a function returns NULL or an >>> ERR_PTR >>> in the error case. So I have to look at the function code. It's >>> also a >>> typical bug source. >>> We won't solve this in general here. But I think we should be in >>> line >>> with what related functions do. >>> The iomap() functions typically return NULL in the error case. >>> Therefore >>> I'd say any new pcim_...iomap...() function should return NULL too. >>> >>> Then you add support for mapping BAR's partially. I never had such >>> a use >>> case. Are there use cases for this? >>> Maybe we could omit this for now, if it helps to reduce the >>> complexity >>> of the refactoring. >>> >>> I also have bisectability in mind, therefore my personal preference >>> would >>> be to make the single patches as small as possible. Not sure >>> whether there's >>> a way to reduce the size of what currently is the first patch of >>> the series. >>> >>>> Greetings, >>>> P. >>>> >>>> [1] >>>> https://lore.kernel.org/all/20240301112959.21947-1-pstanner@redhat.com/ >>>> >>>> >>>>> >>>>> Note: The check for !pci_resource_len() is included in >>>>> pcim_iomap(), so we don't have to duplicate it. >>>>> >>>>> Make r8169 the first user of the new function. >>>>> >>>>> I'd prefer to handle this via the PCI tree. >>>>> >>>>> Heiner Kallweit (2): >>>>>   PCI: Add pcim_iomap_region >>>>>   r8169: use new function pcim_iomap_region() >>>>> >>>>>  drivers/net/ethernet/realtek/r8169_main.c |  8 +++---- >>>>>  drivers/pci/devres.c                      | 28 >>>>> +++++++++++++++++++++++ >>>>>  include/linux/pci.h                       |  2 ++ >>>>>  3 files changed, 33 insertions(+), 5 deletions(-) >>>>> >>>> >>> >>> Heiner >> >