From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] mpt3sas: Use 63-bit DMA addressing on SAS35 HBA Date: Fri, 26 Jul 2019 07:27:06 -0700 Message-ID: <20190726142706.GA1734@infradead.org> References: <1564135257-33188-1-git-send-email-suganath-prabu.subramani@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1564135257-33188-1-git-send-email-suganath-prabu.subramani@broadcom.com> Sender: stable-owner@vger.kernel.org To: Suganath Prabu Cc: linux-scsi@vger.kernel.org, stable@vger.kernel.org, Sathya.Prakash@broadcom.com, kashyap.desai@broadcom.com, sreekanth.reddy@broadcom.com List-Id: linux-scsi@vger.kernel.org On Fri, Jul 26, 2019 at 06:00:57AM -0400, Suganath Prabu wrote: > Although SAS3 & SAS3.5 IT HBA controllers support > 64-bit DMA addressing, as per hardware design, > DMA address with all 64-bits set (0xFFFFFFFF-FFFFFFFF) > results in a firmware fault. Linux will never send a dma address with all bits set anyway, as that is our magic escape for the dma_addr_t error value. Additionally to generate that address you'd need a 1-byte sized, 1-byte aligned buffer, which we never use.