From patchwork Wed Oct 7 23:55:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11821947 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2C3B41580 for ; Wed, 7 Oct 2020 23:55:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16BA620714 for ; Wed, 7 Oct 2020 23:55:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728976AbgJGXzj (ORCPT ); Wed, 7 Oct 2020 19:55:39 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:45878 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728951AbgJGXzg (ORCPT ); Wed, 7 Oct 2020 19:55:36 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id 478AF803086A; Wed, 7 Oct 2020 23:55:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at baikalelectronics.ru Received: from mail.baikalelectronics.ru ([127.0.0.1]) by localhost (mail.baikalelectronics.ru [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id g6s_lKlK-klo; Thu, 8 Oct 2020 02:55:28 +0300 (MSK) From: Serge Semin To: Mark Brown , Serge Semin CC: Serge Semin , Alexey Malahov , Ramil Zaripov , Pavel Parkhomenko , Andy Shevchenko , Andy Shevchenko , Lars Povlsen , "wuxu . wu" , Feng Tang , Rob Herring , , , Subject: [PATCH v4 18/21] spi: dw: Introduce max mem-ops SPI bus frequency setting Date: Thu, 8 Oct 2020 02:55:07 +0300 Message-ID: <20201007235511.4935-19-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20201007235511.4935-1-Sergey.Semin@baikalelectronics.ru> References: <20201007235511.4935-1-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org In some circumstances the current implementation of the SPI memory operations may occasionally fail even though they are executed in the atomic context. This may happen if the system bus is relatively slow in comparison to the SPI bus frequency, or there is a concurrent access to it, which makes the MMIO-operations occasionally stalling before push-pulling data from the DW APB SPI FIFOs. These two problems we've discovered on the Baikal-T1 SoC. In order to fix them we have no choice but to set an artificial limitation on the SPI bus speed. Note currently this limitation will be only applicable for the memory operations, since the standard SPI core interface is implemented with an assumption that there is no problem with the automatic CS toggling. Signed-off-by: Serge Semin --- drivers/spi/spi-dw-core.c | 4 +++- drivers/spi/spi-dw.h | 1 + 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c index 8eb3b31b376d..bcfa224e0e43 100644 --- a/drivers/spi/spi-dw-core.c +++ b/drivers/spi/spi-dw-core.c @@ -629,7 +629,7 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op) * operation. Transmit-only mode is suitable for the rest of them. */ cfg.dfs = 8; - cfg.freq = mem->spi->max_speed_hz; + cfg.freq = clamp(mem->spi->max_speed_hz, 0U, dws->max_mem_freq); if (op->data.dir == SPI_MEM_DATA_IN) { cfg.tmode = SPI_TMOD_EPROMREAD; cfg.ndf = op->data.nbytes; @@ -717,6 +717,8 @@ static void dw_spi_init_mem_ops(struct dw_spi *dws) dws->mem_ops.adjust_op_size = dw_spi_adjust_mem_op_size; dws->mem_ops.supports_op = dw_spi_supports_mem_op; dws->mem_ops.exec_op = dw_spi_exec_mem_op; + if (!dws->max_mem_freq) + dws->max_mem_freq = dws->max_freq; } } diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h index 4b08fe34a85d..dc5781236cc6 100644 --- a/drivers/spi/spi-dw.h +++ b/drivers/spi/spi-dw.h @@ -148,6 +148,7 @@ struct dw_spi { unsigned long paddr; int irq; u32 fifo_len; /* depth of the FIFO buffer */ + u32 max_mem_freq; /* max mem-ops bus freq */ u32 max_freq; /* max bus freq supported */ u32 caps; /* DW SPI capabilities */