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[2a01:c23:b9be:3500:9016:a3de:1f88:2f89]) by smtp.googlemail.com with ESMTPSA id l3-20020a5d5603000000b0033e03d37685sm2240607wrv.55.2024.03.28.10.35.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Mar 2024 10:35:40 -0700 (PDT) Message-ID: <348fa275-3922-4ad1-944e-0b5d1dd3cff5@gmail.com> Date: Thu, 28 Mar 2024 18:35:40 +0100 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 , Realtek linux nic maintainers , Paolo Abeni , Jakub Kicinski , Eric Dumazet , David Miller Cc: "linux-pci@vger.kernel.org" , "netdev@vger.kernel.org" References: <982b02cb-a095-4131-84a7-24817ac68857@gmail.com> <4cf0d7710a74095a14bedc68ba73612943683db4.camel@redhat.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: <4cf0d7710a74095a14bedc68ba73612943683db4.camel@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. 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