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[2620:137:e000::1:20]) by mx.google.com with ESMTP id ko13-20020a17090307cd00b0019cf1bde932si1638091plb.35.2023.03.10.01.28.44; Fri, 10 Mar 2023 01:28:57 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230447AbjCJJ0j (ORCPT + 99 others); Fri, 10 Mar 2023 04:26:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230430AbjCJJ0H (ORCPT ); Fri, 10 Mar 2023 04:26:07 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A746610A2B0 for ; Fri, 10 Mar 2023 01:22:05 -0800 (PST) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1paYwN-0002lF-P7; Fri, 10 Mar 2023 10:21:31 +0100 Received: from [2a0a:edc0:0:1101:1d::39] (helo=dude03.red.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.94.2) (envelope-from ) id 1paYwM-0038yl-36; Fri, 10 Mar 2023 10:21:30 +0100 Received: from lgo by dude03.red.stw.pengutronix.de with local (Exim 4.94.2) (envelope-from ) id 1paYwL-004Dqb-De; Fri, 10 Mar 2023 10:21:29 +0100 From: =?utf-8?q?Leonard_G=C3=B6hrs?= To: Alain Volmat , Mark Brown , Maxime Coquelin , Alexandre Torgue Cc: kernel@pengutronix.de, =?utf-8?q?Leonard_G=C3=B6hrs?= , linux-spi@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v1 2/2] spi: stm32: split large transfers based on word size instead of bytes Date: Fri, 10 Mar 2023 10:20:53 +0100 Message-Id: <20230310092053.1006459-2-l.goehrs@pengutronix.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230310092053.1006459-1-l.goehrs@pengutronix.de> References: <20230310092053.1006459-1-l.goehrs@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: lgo@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759972464370089723?= X-GMAIL-MSGID: =?utf-8?q?1759972464370089723?= The TSIZE register in CR2, to which the number of words to transfer is written, is only 16 Bit. This limits transfers to 65535 SPI _words_ at a time. The existing code uses spi_split_transfers_maxsize to limit transfers to 65535 _bytes_ at a time. This breaks large transfers with bits_per_word > 8, as they are split inside of a word boundary by the odd size limit. Split transfers based on the number of words instead. This has the added benefit of not artificially limiting the maximum length of bpw > 8 transfers to half or a quarter of the actual limit. The combination of very large transfers and bits_per_word = 16 is triggered e.g. by MIPI DBI displays when updating large parts of the screen. Signed-off-by: Leonard Göhrs Acked-by: Alain Volmat --- drivers/spi/spi-stm32.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c index def09cf0dc14..d2e16f16fae6 100644 --- a/drivers/spi/spi-stm32.c +++ b/drivers/spi/spi-stm32.c @@ -984,9 +984,9 @@ static int stm32_spi_prepare_msg(struct spi_master *master, if (spi->cfg->set_number_of_data) { int ret; - ret = spi_split_transfers_maxsize(master, msg, - STM32H7_SPI_TSIZE_MAX, - GFP_KERNEL | GFP_DMA); + ret = spi_split_transfers_maxwords(master, msg, + STM32H7_SPI_TSIZE_MAX, + GFP_KERNEL | GFP_DMA); if (ret) return ret; }