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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?L1HVEUUD3TVGlL6jXJYcLEHz3vJtAu138KcrwQVqD65eoULsaYjRHHfLQh4z?= =?us-ascii?Q?U6NLnRBukuyq/4inwmyxIUV4RBGIBYZOwwDZFIW8woo//DPd9U0wUNZOJ9qI?= =?us-ascii?Q?DG0P3SpeW8bcUSlJIGVZ4f9wa2Hp+XNvwgehedW9EYyvxgRKzEgz1d1A/qln?= =?us-ascii?Q?VHGvsYLQpo/FyNRezPrb1D9cBbm1fkqvD+Am79CPgyvHj0vQxi41t8iNV3wm?= =?us-ascii?Q?H/bTkpEWVMkXZe5LOIaGSJO5fojMF5FBuK0+RLV5l4VYDr9JGM1AHnYkBBdN?= =?us-ascii?Q?J1ZJrqRby3uVIcolp7vdRAMBZa0yCoPSlTntriUiOEO0TfOaIHq1f1E9bMXb?= =?us-ascii?Q?AponAwwhAY5mqD85Twq5EuFUpmBtGvdYH0Kcp169zpVRnoCD9N3bTfbvX+Kr?= =?us-ascii?Q?0x70GegObI7xffR64vnpy7fJVG/qYHJUsxGpzvwYNCb3l166Anu/7Ndkhjj6?= =?us-ascii?Q?L2kOkvAkHwsIBXg8LF7Hx+7lGEtcKNZxu4cHxg4Q8DKBsr66MZOmpmDjwdsV?= =?us-ascii?Q?YWl9bPaF1WppTzFtmMCmjWTWInVSNWYIm6rbtERqR6LgibmwK1u64vysCtUV?= =?us-ascii?Q?znS6KdJ813ynExuoZlLx4JEtJgBwzqhHT6vp+qkHstrf/XxH+Lk9jrPFzgOj?= =?us-ascii?Q?OMG8ZWtGYbdtd57gWth5LkCx4rzlmVman6cpD+98Yjy+4mNGJ/VX8jVi/3a4?= =?us-ascii?Q?fpzyZUq0+v6Qn3NfU9JhmzLJXOBzudhrZAReB5eSgjCf2IoOb+Ep3WFFqiOM?= =?us-ascii?Q?l11Mn2BKZTIA2Q75PxgVv6ASojmS9AEW98/V4Zi9Bhteu4BoxzvphUh7wr6U?= =?us-ascii?Q?T6LKJ4a4yoMB2v1T1fGmqdZKONtNOvWaznA4Mtt087XHXlEUXccXPkNLQqvF?= =?us-ascii?Q?K/3qZ2sYveymVCt6Ceonf92iXcMr/b6ByyqUizEeZy7HRvoQZt7dSGYK756q?= =?us-ascii?Q?fkMW45wzVWMOX4aHqKgTYBZy8vjKBPFD9ODY0JpBGhXk4FCc5Fo6JqtSUzRa?= =?us-ascii?Q?Ll1RbxONkk0ihfMQSj0geXV01yzy7P3adaC2yHP4AFb3oET17w4anxnuTfmb?= =?us-ascii?Q?iHwB6BVaI09lCgwTVAp3SUp3pIlEFQWHiomKx63w8L/0D/RZKMmKpYi35ukV?= =?us-ascii?Q?/YjswttDUINzQcfaGedxa/gYw/VLDxQkg5Jz2YRdUqPhqYjmmRtKJGNicfVh?= =?us-ascii?Q?8ta4yYglNnYqfuhJUBpshUrfiveZ+VWVKZ5zdJDBZ4X9kOn+GX6ay0kIBgFb?= =?us-ascii?Q?LfkktChaPYiS6hugsbbb1gbKL+5oS68T+pnphn60rpkekAO3M0/DvF3rcXcV?= =?us-ascii?Q?ByR7xgJlhA8QxMvpr+0GK1pC7TRYZybhR8kQy6KV98rOdoWK57rJau84fxSl?= =?us-ascii?Q?+PMAkZzN5Bt2o6hudFtyAX7VPZ/HEbOG3Ale/3uJTbLh6X/gVggytGFmP69p?= =?us-ascii?Q?MbyvCyg4AMWOslUdp+euI6QeGmlfRRidl0WFAzUX/MAKoYm0RMTmGYM+cTcV?= =?us-ascii?Q?av5TBpy1KFO0vn/dGSB62QNOm9ezxFIA//132FzDGpDgLWus+h9ss3pUMe2j?= =?us-ascii?Q?gzLfB4sxdhiK0WAHadRtHSOxMI71nJQ41Mf9nI28CLlscrY93nvx8yQqmuyv?= =?us-ascii?Q?JWEsP3IrcQljt+8T+6Ragrne37BN2irkr/BOUqyxXkMhUkURK8YVa0EQHVT4?= =?us-ascii?Q?MkyT8A=3D=3D?= X-OriginatorOrg: corigine.com X-MS-Exchange-CrossTenant-Network-Message-Id: a805750f-8ef4-4c1d-e729-08db5847e4db X-MS-Exchange-CrossTenant-AuthSource: PH0PR13MB4842.namprd13.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 May 2023 09:03:20.9918 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: fe128f2c-073b-4c20-818e-7246a585940c X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: tP5AwSSGhHRTgacTpbbjuWS31uK827yBgS0fes5wyGQcpMajtaYSn9ye2PHOBlu8O7cbNSfjtGElilJVQhHYRrP42QP04XUksleWGUz8f/Y= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR13MB6541 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 18, 2023 at 11:29:13AM +0200, Oleksij Rempel wrote: > This patch introduces the function 'ksz8_downstream_link_up' to the > Microchip KSZ8xxx driver. This function configures the flow control settings > for the downstream ports of the switch based on desired settings and the > current duplex mode. > > The KSZ8795 switch, unlike the KSZ8873, supports asynchronous pause control. > However, a single bit controls both RX and TX pause, so we can't enforce > asynchronous pause control. The flow control can be set based on the > auto-negotiation process, depending on the capabilities of both link partners. > > For the KSZ8873, the PORT_FORCE_FLOW_CTRL bit can be set by the hardware > bootstrap, ignoring the auto-negotiation result. Therefore, even in > auto-negotiation mode, we need to ensure that the PORT_FORCE_FLOW_CTRL bit is > correctly set. > > In the absence of auto-negotiation, we will enforce synchronous pause control > for the KSZ8795 switch. > > Note: It is currently not possible to force disable flow control on a port if > we still advertise pause support. This configuration is not currently supported > by Linux, and it may not make practical sense. However, it's essential to > understand this limitation when working with the KSZ8873 and similar devices. > > Signed-off-by: Oleksij Rempel Reviewed-by: Simon Horman > +static void ksz8_downstream_link_up(struct ksz_device *dev, int port, > + int duplex, bool tx_pause, bool rx_pause) > +{ > + const u16 *regs = dev->info->regs; > + u8 ctrl = 0; > + int ret; > + > + /* > + * The KSZ8795 switch differs from the KSZ8873 by supporting > + * asynchronous pause control. However, since a single bit is used to > + * control both RX and TX pause, we can't enforce asynchronous pause > + * control - both TX and RX pause will be either enabled or disabled > + * together. > + * > + * If auto-negotiation is enabled, we usually allow the flow control to > + * be determined by the auto-negotiation process based on the > + * capabilities of both link partners. However, for KSZ8873, the > + * PORT_FORCE_FLOW_CTRL bit may be set by the hardware bootstrap, > + * ignoring the auto-negotiation result. Thus, even in auto-negotiatio > + * mode, we need to ensure that the PORT_FORCE_FLOW_CTRL bit is > + * properly cleared. > + * > + * In the absence of auto-negotiation, we will enforce synchronous > + * pause control for both variants of switches - KSZ8873 and KSZ8795. > + */ nit: multi-line comments in networking code are like this: /* This is * a wrap. */ ...