From patchwork Tue Nov 12 17:55:23 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kars de Jong X-Patchwork-Id: 11239943 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 1762D159A for ; Tue, 12 Nov 2019 17:55:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0106221872 for ; Tue, 12 Nov 2019 17:55:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727164AbfKLRzi (ORCPT ); Tue, 12 Nov 2019 12:55:38 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:34798 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725997AbfKLRzi (ORCPT ); Tue, 12 Nov 2019 12:55:38 -0500 Received: by mail-wr1-f67.google.com with SMTP id e6so19622689wrw.1; Tue, 12 Nov 2019 09:55:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=PKqltzNuj9+V9K/S4mkpmqKkAX19ynUBErL0SLJsqZs=; b=b9mqxNVW7eA3ZPer+6ZW85xiC+6m2223omOhpaR+qIVF8D3+bvy9CdNeNzinyU7gEU Bc/qPwjm9qSJuKDeMfCp6088PeKwY47P3BiWUYol2yxUUx9vgxhD4CC2o9I7m7WTCIWC ZyoVgVf218/rgoFiVGJ5teRJXa1kXJm6oqrlRiWrnvFywbGK2gSL4DFkxUour3QrFFkw ugCXRrCm1TC4OoHGSkA6e/oAvIUcbdUimbkzGv7jbFm6wZYHN9pcnnAJvMV0w3ql6uMe xDEKf4mw5Yo4wGXY9zPrCPJknTwFgA6P7gd10tCEpODBNbV8cmBbFaO7zMMGQaXZWJHW aRIA== X-Gm-Message-State: APjAAAUYKeRkxNZS+aVg/pomvCmW3+P6f/5Itx78azG8tPf7DnAgxyKA t4ugIpMxY6+ohrvEd2zcwLg= X-Google-Smtp-Source: APXvYqxLiPDWnqkcjTCaRSjaKyoD44ZA0f5SKqdVCMWFCU45LZWQ10JagIAJdQGDMjlZn5wYhdgF6Q== X-Received: by 2002:a5d:6412:: with SMTP id z18mr26462034wru.30.1573581335747; Tue, 12 Nov 2019 09:55:35 -0800 (PST) Received: from localhost.localdomain (82-75-169-199.cable.dynamic.v4.ziggo.nl. [82.75.169.199]) by smtp.gmail.com with ESMTPSA id a8sm4229125wme.11.2019.11.12.09.55.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Nov 2019 09:55:35 -0800 (PST) From: Kars de Jong To: "James E.J. Bottomley" Cc: linux-scsi@vger.kernel.org, linux-m68k@vger.kernel.org, "Martin K. Petersen" , schmitzmic@gmail.com, fthain@telegraphics.com.au, Kars de Jong Subject: [PATCH v2] zorro_esp: Limit DMA transfers to 65536 bytes (except on Fastlane) Date: Tue, 12 Nov 2019 18:55:23 +0100 Message-Id: <20191112175523.23145-1-jongk@linux-m68k.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <1573414513.3230.4.camel@linux.ibm.com> References: <1573414513.3230.4.camel@linux.ibm.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org When using this driver on a Blizzard 1260, there were failures whenever DMA transfers from the SCSI bus to memory of 65535 bytes were followed by a DMA transfer of 1 byte. This caused the byte at offset 65535 to be overwritten with 0xff. The Blizzard hardware can't handle single byte DMA transfers. Besides this issue, limiting the DMA length to something that is not a multiple of the page size is very inefficient on most file systems. It seems this limit was chosen because the DMA transfer counter of the ESP by default is 16 bits wide, thus limiting the length to 65535 bytes. However, the value 0 means 65536 bytes, which is handled by the ESP and the Blizzard just fine. It is also the default maximum used by esp_scsi when drivers don't provide their own dma_length_limit() function. The limit of 65536 bytes can be used by all boards except the Fastlane. The old driver used a limit of 65532 bytes (0xfffc), which is reintroduced in this patch. Fixes: b7ded0e8b0d1 ("scsi: zorro_esp: Limit DMA transfers to 65535 bytes") Signed-off-by: Kars de Jong Reviewed-by: Finn Thain --- drivers/scsi/zorro_esp.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/zorro_esp.c b/drivers/scsi/zorro_esp.c index ca8e3abeb2c7..a23a8e5794f5 100644 --- a/drivers/scsi/zorro_esp.c +++ b/drivers/scsi/zorro_esp.c @@ -218,7 +218,14 @@ static int fastlane_esp_irq_pending(struct esp *esp) static u32 zorro_esp_dma_length_limit(struct esp *esp, u32 dma_addr, u32 dma_len) { - return dma_len > 0xFFFF ? 0xFFFF : dma_len; + return dma_len > (1U << 16) ? (1U << 16) : dma_len; +} + +static u32 fastlane_esp_dma_length_limit(struct esp *esp, u32 dma_addr, + u32 dma_len) +{ + /* The old driver used 0xfffc as limit, so do that here too */ + return dma_len > 0xfffc ? 0xfffc : dma_len; } static void zorro_esp_reset_dma(struct esp *esp) @@ -604,7 +611,7 @@ static const struct esp_driver_ops fastlane_esp_ops = { .esp_write8 = zorro_esp_write8, .esp_read8 = zorro_esp_read8, .irq_pending = fastlane_esp_irq_pending, - .dma_length_limit = zorro_esp_dma_length_limit, + .dma_length_limit = fastlane_esp_dma_length_limit, .reset_dma = zorro_esp_reset_dma, .dma_drain = zorro_esp_dma_drain, .dma_invalidate = fastlane_esp_dma_invalidate,